OCR Triple Science: Physics — Recall & Retrieval

P1.1a Describe how and why the atomic model has changed over time

1.

What was Thomson's model of the atom called?

The plum pudding model.

2.

What did Rutherford discover about the structure of the atom?

Rutherford discovered that the atom has a very small, dense, positively charged nucleus and that most of the atom is empty space.

3.

How did the gold foil experiment change the atomic model?

Most alpha particles passed straight through the gold foil, but some were deflected and a very small number bounced back. This showed that the positive charge and most of the mass were concentrated in a tiny nucleus, disproving the plum pudding model.

4.

What did Bohr add to Rutherford's model of the atom?

Bohr proposed that electrons orbit the nucleus in fixed energy levels or shells.

5.

Explain why the atomic model has changed over time.

The atomic model has changed as new experimental evidence has been discovered. Scientists changed or replaced models when they could no longer explain the experimental results.

6.

Compare the Thomson, Rutherford and Bohr models of the atom.

Thomson's model was a sphere of positive charge containing negative electrons. Rutherford's model had a small positive nucleus surrounded by electrons, with mostly empty space between them. Bohr developed Rutherford's model by placing the electrons in fixed energy levels or shells around the nucleus.

P1.1b Describe the atom as a positively charged nucleus surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with almost all of the mass in the nucleus

1.

What is found in the centre of an atom?

The nucleus.

2.

What charge do electrons have?

Negative charge.

3.

Where is almost all of the mass of an atom found?

In the nucleus.

4.

How does the size of the nucleus compare with the size of the atom?

The radius of the nucleus is much smaller than the radius of the whole atom.

5.

Describe the structure of an atom.

An atom consists of a tiny, positively charged nucleus containing protons and neutrons, surrounded by negatively charged electrons.

6.

Explain why atoms are mostly empty space.

Atoms are mostly empty space because the nucleus occupies only a tiny fraction of the atom's total volume and the electrons are found much further away from the nucleus.

P1.1c Recall the typical size (order of magnitude) of atoms and small molecules

1.

What is the typical size of an atom?

Approximately 1 × 10⁻¹⁰ m.

2.

State the order of magnitude of a small molecule.

Approximately 10⁻¹⁰ m.

3.

What unit is used to measure the size of atoms?

Metres (m), usually expressed using very small powers of ten such as 10⁻¹⁰ m.

4.

Why are atoms difficult to see with the naked eye?

Atoms are extremely small, with typical diameters of about 10⁻¹⁰ m, which is far below what can be resolved by the naked eye.

5.

Explain what is meant by an order of magnitude.

An order of magnitude describes the approximate size of a quantity as a power of ten.

6.

A particle has a diameter of 1 × 10⁻¹⁰ m. Identify the type of particle it could represent.

It could represent an atom because 1 × 10⁻¹⁰ m is a typical atomic diameter.

P1.1d Define density

1.

What is density?

Density is the mass per unit volume of a substance.

2.

State the equation for density.

density = mass / volume.

3.

What are the SI units of density?

kg/m³.

4.

What quantities are needed to calculate density?

Mass and volume.

5.

A block has a mass of 2 kg and a volume of 0.001 m³. Calculate its density.

density = 2 / 0.001 = 2000 kg/m³.

6.

Explain why density is a useful property of a material.

Density is a characteristic physical property that can be used to compare and help identify different materials.

P1.1e Explain the differences in density between the different states of matter in terms of the arrangements of the atoms and molecules

1.

Which state of matter usually has the greatest density?

Solids usually have the greatest density.

2.

Why are gases much less dense than solids?

Gas particles are much further apart, so there is much less mass in a given volume.

3.

Describe the arrangement of particles in a liquid.

Liquid particles are close together but are arranged irregularly and can move past one another.

4.

Explain why solids are generally denser than gases.

In solids, particles are packed closely together, whereas gas particles are widely spaced. Therefore, solids usually contain more mass in the same volume and have a greater density.

5.

How does particle spacing affect density?

The closer together the particles are, the greater the density generally is; greater spacing between particles generally results in a lower density.

6.

Compare the arrangement of particles in solids, liquids and gases and explain how this affects density.

In solids, particles are closely packed in fixed positions. In liquids, particles are also close together but can move past one another. In gases, particles are widely separated. Therefore, solids and liquids are generally much denser than gases.

P1.1f Apply the relationship between density, mass and volume to changes where mass is conserved

1.

State the equation linking density, mass and volume.

density = mass / volume.

2.

A substance has a mass of 4 kg and a density of 800 kg/m³. Calculate its volume.

volume = mass / density = 4 / 800 = 0.005 m³.

3.

A metal block has a volume of 0.005 m³ and a density of 2700 kg/m³. Calculate its mass.

mass = density x volume = 2700 x 0.005 = 13.5 kg.

4.

Explain what is meant by mass being conserved.

Mass being conserved means the total mass remains unchanged during a process.

5.

A solid melts without losing any material. Explain how its density may change even though its mass stays the same.

Its mass remains constant, but its volume may change when it melts. Since density = mass / volume, a change in volume causes its density to change.

6.

A gas is compressed without changing its mass. Explain what happens to its density.

Its volume decreases while its mass remains constant, so its density increases.

P1.2a Describe how mass is conserved when substances melt, freeze, evaporate, condense or sublimate

1.

What is meant by the conservation of mass?

Conservation of mass means that mass is not created or destroyed, so the total mass remains constant.

2.

What happens to the mass of a substance when it melts?

Its mass remains the same.

3.

What happens to the mass of a substance when it freezes?

Its mass remains the same.

4.

Why is mass conserved during evaporation and condensation in a closed system?

During evaporation and condensation, particles change their arrangement but are not created or destroyed. In a closed system, none of the particles can escape, so the total mass remains constant.

5.

What is sublimation?

Sublimation is when a substance changes directly from a solid to a gas without becoming a liquid.

6.

Explain why mass remains the same during changes of state.

During a change of state, the particles are rearranged but no particles are created or destroyed, so the total mass remains the same.

P1.2b Describe that physical changes differ from chemical changes because the material recovers its original properties if the change is reversed

1.

What is a physical change?

A physical change is a change in which no new substance is formed and the original properties can be recovered if the change is reversed.

2.

What is a chemical change?

A chemical change is a change in which one or more new substances are formed.

3.

Why is melting ice a physical change?

Melting ice is a physical change because no new substance is formed; the liquid water can be frozen again to recover the original solid water.

4.

Why is rusting iron a chemical change?

Rusting iron is a chemical change because iron reacts with oxygen to form a new substance, iron oxide.

5.

What happens if a physical change is reversed?

The material recovers its original properties.

6.

Compare a physical change with a chemical change.

A physical change does not produce a new substance and can usually be reversed to recover the original properties, whereas a chemical change produces one or more new substances with different properties.

P1.2c Describe how heating a system will change the energy stored within the system and raise its temperature or produce changes of state

1.

What happens to the internal energy of a substance when it is heated?

Its internal energy increases.

2.

What happens to the temperature of a substance when it is heated but not changing state?

Its temperature increases.

3.

What happens to the energy supplied during a change of state?

The supplied energy increases the internal energy and is used to change the arrangement of the particles rather than increase the temperature.

4.

Why does the temperature stay constant during melting or boiling?

The energy supplied is used to overcome forces between particles and change their arrangement, rather than increasing their kinetic energy.

5.

Explain the difference between heating a substance and changing its state.

Heating without a change of state increases the temperature, whereas during a change of state energy is transferred without a temperature increase.

6.

Describe what happens to the particles when a substance is heated.

The particles gain energy. They usually move or vibrate faster, and if enough energy is supplied, the forces between them can be overcome and the substance changes state.

P1.2d Define the term specific heat capacity and distinguish between it and the term specific latent heat

1.

What is meant by specific heat capacity?

The energy required to raise the temperature of 1 kg of a substance by 1°C.

2.

What is meant by specific latent heat?

The energy required to change the state of 1 kg of a substance without changing its temperature.

3.

What is the difference between specific heat capacity and specific latent heat?

Specific heat capacity relates energy transferred to a temperature change, whereas specific latent heat relates energy transferred to a change of state without a temperature change.

4.

What is specific latent heat of fusion?

The energy required to change 1 kg of a substance from solid to liquid without changing its temperature.

5.

What is specific latent heat of vaporisation?

The energy required to change 1 kg of a substance from liquid to gas without changing its temperature.

6.

Explain why energy is required during a change of state even though the temperature does not increase.

Energy is required to overcome the forces between particles and change their arrangement, so the internal energy increases even though the temperature remains constant.

P1.2e Apply the relationship between change in internal energy of a material and its mass, specific heat capacity and temperature change to calculate the energy change involved

1.

State the equation linking thermal energy, mass, specific heat capacity and temperature change.

change in thermal energy = mass x specific heat capacity x temperature change.

2.

What does specific heat capacity measure?

The energy required to raise the temperature of 1 kg of a substance by 1°C.

3.

A 2 kg block has a specific heat capacity of 500 J/kg°C and is heated by 10°C. Calculate the energy transferred.

energy transferred = 2 x 500 x 10 = 10,000 J.

4.

A material gains 12 000 J of energy. Explain what happens to its internal energy.

Its internal energy increases by 12,000 J.

5.

Why do different materials require different amounts of energy to increase their temperature?

Different materials have different specific heat capacities, so they require different amounts of energy to produce the same temperature increase.

6.

Explain how increasing the mass of a substance affects the energy needed to raise its temperature.

Increasing the mass increases the energy required to produce the same temperature rise. For example, doubling the mass doubles the energy required if specific heat capacity and temperature change remain constant.

P1.2f Apply the relationship between specific latent heat and mass to calculate the energy change involved in a change of state

1.

State the equation linking energy transferred, mass and specific latent heat.

energy transferred = mass x specific latent heat.

2.

What is meant by specific latent heat?

The energy required to change the state of 1 kg of a substance without changing its temperature.

3.

Calculate the energy required to melt 2 kg of a substance with a specific latent heat of fusion of 300 000 J/kg.

energy transferred = 2 x 300,000 = 600,000 J.

4.

Why does the temperature remain constant during a change of state?

The supplied energy is used to overcome forces between particles and change their arrangement rather than increase their kinetic energy, so the temperature remains constant.

5.

Explain why different substances have different values of specific latent heat.

Different substances have different strengths of forces between their particles, so different amounts of energy are required to change their states.

6.

Compare the energy required to melt a substance with the energy required to raise its temperature.

Energy used to melt a substance changes its state without changing its temperature, whereas energy used to raise its temperature increases the particles' kinetic energy and therefore increases temperature.

P1.3a Explain how the motion of the molecules in a gas is related both to its temperature and its pressure

1.

What happens to gas particles when the temperature increases?

The gas particles gain kinetic energy and move faster.

2.

How does increasing the speed of gas particles affect the pressure of a gas?

Faster particles collide with the container walls more frequently and with greater force, increasing the pressure.

3.

Why does heating a gas in a sealed container increase its pressure?

Heating increases the particles' kinetic energy and speed. They collide with the walls more frequently and with greater force, increasing the pressure.

4.

Explain how gas pressure is produced.

Gas pressure is produced by gas particles colliding with the surfaces of their container.

5.

Describe the relationship between the motion of gas particles and temperature.

Higher temperature means the gas particles have greater average kinetic energy and therefore move faster.

6.

Explain why cooling a gas in a closed container decreases its pressure.

Cooling reduces the particles' kinetic energy and speed, so collisions with the container walls are less frequent and less forceful, reducing the pressure.

P1.3b Explain the relationship between the temperature of a gas and its pressure at constant volume (qualitative only)

1.

What happens to the pressure of a gas when its temperature increases at constant volume?

The pressure increases.

2.

What happens to the pressure of a gas when its temperature decreases at constant volume?

The pressure decreases.

3.

Why does increasing the temperature increase the pressure of a gas?

The particles gain kinetic energy and move faster, producing more frequent and more forceful collisions with the container walls.

4.

Why must the volume remain constant for this relationship?

Keeping volume constant ensures that the change in pressure is caused by the change in temperature rather than a change in the space available to the particles.

5.

Describe the relationship between temperature and pressure for a gas at constant volume.

At constant volume, increasing temperature increases pressure, while decreasing temperature decreases pressure.

6.

Explain why the pressure of a gas changes even though its volume remains the same.

Although the volume remains constant, changing the temperature changes the speed and kinetic energy of the particles and therefore changes the frequency and force of their collisions with the walls.

P1.3c Recall that gases can be compressed or expanded by pressure changes and that the pressure produces a net force at right angles to any surface

1.

Why can gases be compressed more easily than liquids?

Gas particles have large spaces between them, so they can be pushed closer together.

2.

What happens to the volume of a gas when the pressure increases?

The volume decreases.

3.

What happens to the volume of a gas when the pressure decreases?

The volume increases.

4.

In which direction does gas pressure act on a surface?

At right angles, or perpendicular, to the surface.

5.

Explain why gas pressure produces a force on the walls of a container.

Gas particles collide with the walls of the container. These collisions exert forces on the walls and produce pressure.

6.

Describe what happens to the particles when a gas is compressed.

The particles become closer together and collide with each other and the container walls more frequently.

P1.3d Explain how increasing the volume in which a gas is contained, at constant temperature, can lead to a decrease in pressure

1.

What happens to the pressure of a gas when its volume increases at constant temperature?

The pressure decreases.

2.

Why does increasing the volume reduce the pressure of a gas?

The particles have more space to move through, so they collide with the container walls less frequently.

3.

What happens to the frequency of particle collisions when the volume increases?

The frequency of collisions with the container walls decreases.

4.

Explain why Boyle's law applies only at constant temperature.

Temperature must remain constant so that the average kinetic energy and speed of the gas particles do not change.

5.

Describe the relationship between pressure and volume for a gas at constant temperature.

At constant temperature, pressure is inversely related to volume: increasing volume decreases pressure and decreasing volume increases pressure.

6.

Explain why reducing the volume of a gas increases its pressure.

Reducing the volume gives the particles less space, causing more frequent collisions with the container walls and therefore increasing the pressure.

P1.3e Explain how doing work on a gas can increase its temperature

1.

What is meant by doing work on a gas?

Doing work on a gas means transferring energy to it by applying a force that compresses it.

2.

What happens to the temperature of a gas when it is compressed?

Its temperature increases.

3.

Why does compressing a gas increase its temperature?

Work done on the gas transfers energy to its internal energy store, increasing the average kinetic energy of its particles and therefore its temperature.

4.

Explain what happens inside a bicycle pump when air is compressed.

The piston compresses the air, doing work on the gas. The gas gains internal energy and its temperature rises.

5.

Describe the energy changes when work is done on a gas.

Energy is transferred mechanically to the gas, increasing its internal energy.

6.

Explain why a bicycle pump becomes warm after repeated use.

Repeated compression means work is done on the air in the pump. Some of this energy increases the internal energy of the gas and pump, causing the pump to become warm.

P1.3f Describe a simple model of the Earth's atmosphere and of atmospheric pressure

1.

What is atmospheric pressure?

Atmospheric pressure is the pressure exerted by the Earth's atmosphere.

2.

What causes atmospheric pressure?

It is caused by air particles colliding with surfaces and by the weight of the atmosphere.

3.

Why does the Earth's atmosphere exert pressure on objects?

Air particles are constantly moving and colliding with surfaces, exerting forces on them.

4.

Describe a simple model of the Earth's atmosphere.

The atmosphere can be modelled as a layer of gas surrounding the Earth, held in place by gravity.

5.

Why is the atmosphere assumed to have a uniform density in the simple model?

Assuming uniform density simplifies the model and makes the behaviour of the atmosphere easier to describe and calculate.

6.

Explain how atmospheric pressure is produced.

Atmospheric pressure is produced by the weight of the air above a surface and by moving air particles colliding with that surface.

P1.3g Explain why atmospheric pressure varies with height above the surface of the planet

1.

What happens to atmospheric pressure as height above the Earth's surface increases?

Atmospheric pressure decreases as height increases.

2.

Why is atmospheric pressure greatest at sea level?

At sea level there is a greater column of air above a surface, so the weight of the air produces a greater pressure.

3.

Explain why atmospheric pressure decreases with altitude.

At higher altitudes there is less air above a surface, so the weight of the atmosphere pressing down is smaller.

4.

Why is there less air above you at higher altitudes?

Because most of the atmosphere is below you and there is a smaller column of air above you.

5.

Describe the relationship between atmospheric pressure and height.

Atmospheric pressure decreases as height above the Earth's surface increases.

6.

Explain why climbers experience lower atmospheric pressure on mountains.

On a mountain there is less atmosphere above the climber, so the weight of air above them is lower and therefore the atmospheric pressure is lower.

P1.3h Describe the factors which influence floating and sinking

1.

What is meant by floating?

Floating is when an object remains at or near the surface of a fluid because the upward force balances its weight.

2.

What is meant by sinking?

Sinking is when an object moves down through a fluid because its weight is greater than the upward force.

3.

How does the density of an object affect whether it floats or sinks?

An object generally floats if its average density is less than the fluid and sinks if its average density is greater than the fluid.

4.

How does the density of a liquid affect whether an object floats?

A denser liquid can provide a greater upward force, making it easier for an object to float.

5.

Explain why an object floats when the upward force is equal to its weight.

When the upward force equals the object's weight, the resultant vertical force is zero, so the object does not accelerate upwards or downwards and floats.

6.

Describe the factors that determine whether an object will float or sink.

Whether an object floats or sinks depends on its weight, the upward force from the fluid, and the densities of the object and fluid.

P1.3i Explain why pressure in a liquid varies with depth and density and how this leads to an upwards force on a partially submerged object

1.

What happens to liquid pressure as depth increases?

Liquid pressure increases as depth increases.

2.

How does the density of a liquid affect its pressure?

A denser liquid produces a greater pressure at the same depth.

3.

Why is the pressure greater at the bottom of a submerged object than at the top?

The bottom of the object is at a greater depth, so the liquid pressure there is greater than at the top.

4.

What is the name of the upward force acting on an object in a liquid?

Upthrust.

5.

Explain how differences in liquid pressure produce an upward force on a partially submerged object.

The greater pressure acting upwards on the lower surfaces produces a larger force than the pressure acting downwards on the upper surfaces, resulting in a net upward force.

6.

Explain why an object experiences a greater upward force in a denser liquid.

A denser liquid produces a greater pressure difference between the top and bottom of the object, producing a greater resultant upward force.

P1.3j Calculate the differences in pressure at different depths in a liquid

1.

State the equation linking pressure difference, liquid density, gravitational field strength and depth.

pressure difference = liquid density x gravitational field strength x depth.

2.

What value should be used for gravitational field strength near the Earth's surface?

Approximately 10 N/kg.

3.

Calculate the pressure difference at a depth of 2 m in water of density 1000 kg/m³.

pressure difference = 1000 x 10 x 2 = 20,000 Pa.

4.

Calculate the pressure difference between depths of 1 m and 4 m in water of density 1000 kg/m³.

Difference in depth = 4 - 1 = 3 m. Pressure difference = 1000 x 10 x 3 = 30,000 Pa.

5.

A liquid has a density of 800 kg/m³. Calculate the pressure difference at a depth of 5 m.

pressure difference = 800 x 10 x 5 = 40,000 Pa.

6.

Explain how increasing the depth or density of a liquid affects the pressure difference.

Increasing either the depth or the density increases the pressure difference proportionally because pressure difference = density x gravitational field strength x depth.

P2.1a Describe how to measure distance and time in a range of scenarios

1.

Which instrument can be used to measure a short distance accurately?

A ruler or tape measure.

2.

Which instrument can be used to measure the time taken for an event?

A stopwatch or stopclock.

3.

How could you measure the distance travelled by a person walking across a playground?

Measure the distance using a tape measure or trundle wheel.

4.

How could you measure the time taken for a trolley to travel down a ramp?

Use a stopwatch, or light gates connected to a data logger for greater accuracy.

5.

Why should repeated measurements be taken when measuring distance and time?

To identify anomalous results and calculate a mean, improving the reliability of the results.

6.

Describe how to measure the distance and time taken by a moving object in an investigation.

Measure the distance travelled using an appropriate measuring instrument, measure the time taken with a stopwatch or electronic timer, repeat the measurements and calculate a mean time.

P2.1b Describe how to measure distance and time and use these to calculate speed

1.

State the equation linking speed, distance and time.

speed = distance / time.

2.

What units are normally used for speed?

m/s (metres per second).

3.

A runner travels 100 m in 12.5 s. Calculate the runner's speed.

speed = 100 / 12.5 = 8 m/s.

4.

A car travels 450 m in 30 s. Calculate its speed.

speed = 450 / 30 = 15 m/s.

5.

Describe how you could measure the speed of a student walking along a corridor.

Measure the distance travelled with a tape measure, measure the time using a stopwatch and calculate the speed using speed = distance / time.

6.

Explain how distance and time measurements can be used to calculate speed.

Measure the distance travelled and the time taken, then divide the distance by the time to calculate the speed.

P2.1c Make calculations using ratios and proportional reasoning to convert units and to compute rates

1.

Convert 5 km into metres.

5000 m.

2.

Convert 3 minutes into seconds.

180 s.

3.

Convert a speed of 72 km/h into m/s.

20 m/s.

4.

A cyclist travels 1500 m in 5 minutes. Calculate the cyclist's speed in m/s.

Time = 5 minutes = 300 s. Speed = 1500 / 300 = 5 m/s.

5.

A car travels at 20 m/s. Calculate its speed in km/h.

72 km/h.

6.

Explain why units must be converted before using them in speed calculations.

Units must be consistent. For example, distance should be in metres and time in seconds to obtain speed in m/s.

P2.1d Explain the vector–scalar distinction as it applies to displacement and distance, velocity and speed

1.

What is a scalar quantity?

A quantity with magnitude only.

2.

What is a vector quantity?

A quantity with both magnitude and direction.

3.

Why is distance a scalar quantity?

Distance has magnitude only and no direction.

4.

Why is displacement a vector quantity?

Displacement includes both the distance moved and the direction.

5.

Explain the difference between speed and velocity.

Speed is a scalar quantity, whereas velocity is a vector quantity because it includes direction.

6.

A student walks 5 m east and then 5 m west. State the distance travelled and the final displacement.

Distance travelled = 10 m. Final displacement = 0 m.

P2.1e Relate changes and differences in motion to appropriate distance–time and velocity–time graphs; interpret lines and slopes

1.

What does the gradient of a distance–time graph represent?

Speed.

2.

What does a horizontal line on a distance–time graph show?

The object is stationary.

3.

What does the gradient of a velocity–time graph represent?

Acceleration.

4.

What does a straight sloping line on a distance–time graph show?

The object is moving at a constant speed.

5.

Explain how acceleration is shown on a velocity–time graph.

Acceleration is shown by the gradient of the velocity–time graph. A steeper gradient represents a greater acceleration.

6.

Describe how a distance–time graph changes when an object moves at a greater speed.

The graph becomes steeper because a greater gradient represents a greater speed.

P2.1f Interpret enclosed area in velocity–time graphs

1.

What does the area under a velocity–time graph represent?

Distance travelled.

2.

How is the area under a rectangular section of a velocity–time graph calculated?

Area = base × height.

3.

An object travels at 8 m/s for 5 s. Calculate the distance travelled using the graph area.

Distance = 8 × 5 = 40 m.

4.

A velocity–time graph forms a triangle with a base of 6 s and a height of 10 m/s. Calculate the distance travelled.

Distance = ½ × 6 × 10 = 30 m.

5.

Why can the area under a velocity–time graph be divided into simple shapes?

Because rectangles and triangles have simple area formulae that can be added together to find the total area.

6.

Explain how to calculate the total distance travelled from a velocity–time graph containing rectangles and triangles.

Calculate the area of each rectangle and triangle separately, then add the areas together to find the total distance travelled.

P2.1g Calculate average speed for non-uniform motion

1.

What is meant by non-uniform motion?

Motion in which the speed changes.

2.

State the equation used to calculate average speed.

average speed = total distance / total time.

3.

A cyclist travels 600 m in 40 s. Calculate the average speed.

Average speed = 600 / 40 = 15 m/s.

4.

A runner completes 5 km in 25 minutes. Calculate the average speed in m/s.

5 km = 5000 m. 25 minutes = 1500 s. Average speed = 5000 / 1500 = 3.33 m/s.

5.

Why may an object's instantaneous speed differ from its average speed?

Instantaneous speed is the speed at one particular moment, whereas average speed is calculated over the whole journey.

6.

A car travels 20 km in 30 minutes and then 40 km in 45 minutes. Calculate its average speed for the whole journey.

Total distance = 20 km + 40 km = 60 km = 60,000 m. Total time = 30 min + 45 min = 75 min = 4500 s. Average speed = 60,000 / 4500 = 13.3 m/s.

P2.1h Apply formulae relating distance, time and speed for uniform motion and for motion with uniform acceleration

1.

What is meant by uniform motion?

Motion at constant speed.

2.

State the equation linking distance, speed and time for uniform motion.

distance = speed × time.

3.

A train travels at a constant speed of 25 m/s for 40 s. Calculate the distance travelled.

Distance = 25 × 40 = 1000 m.

4.

A car travels 300 m at a constant speed of 15 m/s. Calculate the time taken.

Time = 300 / 15 = 20 s.

5.

An object accelerates uniformly from 4 m/s to 16 m/s in 6 s. Calculate its average speed.

Average speed = (4 + 16) / 2 = 10 m/s.

6.

An object accelerates uniformly from rest to 20 m/s in 8 s. Calculate the distance travelled.

Average speed = (0 + 20) / 2 = 10 m/s. Distance = 10 × 8 = 80 m.

P2.2a Recall examples of ways in which objects interact

1.

What is meant by an interaction between two objects?

An interaction occurs when two objects affect each other by exerting forces on one another.

2.

Give an example of an interaction caused by gravity.

The Earth attracts an object towards its centre, while the object also attracts the Earth.

3.

Give an example of an interaction caused by electrostatic forces.

A charged balloon attracting small pieces of paper.

4.

Give an example of an interaction caused by magnetic forces.

Two magnets attracting or repelling each other.

5.

Give two examples of contact forces.

Friction and normal contact force.

6.

State whether gravity, friction and normal contact force are contact or non-contact forces.

Gravity is a non-contact force. Friction and normal contact force are contact forces.

P2.2b Describe how such examples involve interactions between pairs of objects which produce a force on each object

1.

What happens when two objects interact?

Each object exerts a force on the other object.

2.

Why do forces always act in pairs?

Forces arise from interactions between two objects, so each object experiences a force from the other.

3.

Explain what happens when you push against a wall.

You exert a force on the wall, and the wall exerts an equal and opposite force on you.

4.

Describe the pair of forces acting when a person stands on the ground.

The Earth pulls the person downwards through gravity, while the ground pushes upwards on the person with a normal contact force.

5.

Explain the forces acting between a book and a table.

The book pushes down on the table, and the table pushes upwards on the book with an equal and opposite force.

6.

Describe how two interacting objects each experience a force.

Each object exerts a force on the other. These forces are equal in size, opposite in direction and act on different objects.

P2.2c Represent forces as vectors

1.

What is meant by a vector quantity?

A vector quantity has both magnitude and direction.

2.

What two pieces of information are needed to represent a force as a vector?

The size of the force and its direction.

3.

How is the direction of a force shown on a force diagram?

By an arrow pointing in the direction of the force.

4.

Why is force described as a vector quantity?

Force is described as a vector because it has both size and direction.

5.

Draw and label the forces acting on a book resting on a table.

Draw a box representing the book, with a downward arrow labelled weight and an equal upward arrow labelled normal contact force.

6.

Explain why vector diagrams are useful when analysing forces.

Vector diagrams show the size and direction of forces clearly, allowing the resultant force and whether forces are balanced to be determined.

P2.2d Apply Newton's First Law to explain the motion of an object moving with uniform velocity and also an object where the speed and/or direction change

1.

State Newton's First Law of Motion.

An object remains at rest or continues moving at constant velocity unless acted on by a resultant force.

2.

What happens to an object if the resultant force acting on it is zero?

A stationary object remains stationary, while a moving object continues at constant speed in a straight line.

3.

Why does a passenger move forwards when a car brakes suddenly?

The passenger's body continues moving forwards due to inertia when the car slows down.

4.

Explain why an object moving at constant velocity has zero resultant force.

Constant velocity means there is no acceleration, so the resultant force must be zero.

5.

Describe what happens when the resultant force on an object is no longer zero.

The object accelerates, meaning its speed, direction or both change.

6.

Explain how Newton's First Law applies to a car travelling around a bend.

Although the car's speed may remain constant, its direction changes, so it accelerates towards the centre of the bend. This requires a resultant force towards the centre.

P2.2e Use vector diagrams to illustrate resolution of forces, a net force (resultant force), and equilibrium situations

1.

What is meant by the resultant force?

The resultant force is the single force that has the same effect as all the forces acting together.

2.

What does it mean if an object is in equilibrium?

The forces are balanced and the resultant force is zero.

3.

Two forces of 8 N and 5 N act in opposite directions. Calculate the resultant force.

Resultant force = 8 - 5 = 3 N in the direction of the 8 N force.

4.

Draw a vector diagram to show two equal and opposite forces acting on an object.

Draw two arrows of equal length pointing in opposite directions from the object.

5.

Explain how vector diagrams can be used to find the resultant force.

Forces can be drawn to scale as arrows. Their directions and lengths can then be combined to determine the resultant force.

6.

Describe the forces acting on an object that is in equilibrium.

The forces are equal in size and opposite in direction, so they cancel and produce a resultant force of zero.

P2.2f Describe examples of the forces acting on an isolated solid object or system

1.

What forces act on a skydiver before reaching terminal velocity?

Weight acts downwards and air resistance acts upwards. Before terminal velocity, weight is greater than air resistance.

2.

What forces act on a car travelling at constant speed on a level road?

Driving force acts forwards and resistive forces act backwards. At constant speed, these forces are balanced.

3.

What forces act on a book resting on a table?

Weight acts downwards and the normal contact force from the table acts upwards.

4.

Describe the forces acting on a cyclist moving along a flat road.

The cyclist has a forward driving force, backward air resistance and friction, downward weight and an upward normal contact force.

5.

Explain why the forces acting on a stationary object are balanced.

The forces are equal in size and opposite in direction, giving a resultant force of zero.

6.

Describe the forces acting on a falling object after it reaches terminal velocity.

Weight acts downwards and air resistance acts upwards. At terminal velocity, the forces are equal and balanced.

P2.2g Describe, using free body diagrams, examples where two or more forces lead to a resultant force on an object

1.

What is a free body diagram?

A free body diagram is a diagram showing all the forces acting on one object.

2.

What information is shown on a free body diagram?

It shows each force as a labelled arrow, including its direction and relative size.

3.

Draw a free body diagram for a box being pushed along the floor.

Draw a box with a forward arrow labelled pushing force, a backward arrow labelled friction, a downward arrow labelled weight and an upward arrow labelled normal contact force.

4.

Explain how a free body diagram can be used to identify the resultant force.

Compare the directions and sizes of the arrows. Forces in opposite directions are subtracted to find the resultant.

5.

Describe the forces acting on a parachutist before the parachute opens using a free body diagram.

Draw a longer downward arrow labelled weight and a shorter upward arrow labelled air resistance, showing a resultant force downwards.

6.

Draw a free body diagram for a book resting on a table.

Draw a downward arrow labelled weight and an equal upward arrow labelled normal contact force.

P2.2h Describe, using free body diagrams, examples of special case where forces balance to produce a resultant force of zero (qualitative only)

1.

What is meant by balanced forces?

Balanced forces are equal in size and opposite in direction.

2.

What is the resultant force when forces are balanced?

Zero newtons.

3.

Give an example of an object with balanced forces acting on it.

A book resting on a table.

4.

Draw a free body diagram for a stationary object.

Draw equal-length arrows in opposite directions, such as weight downwards and normal contact force upwards.

5.

Explain why an object moving at constant velocity has balanced forces.

Constant velocity means there is no acceleration, so the resultant force is zero and the forces are balanced.

6.

Describe how a free body diagram shows that forces are balanced.

The arrows representing forces in opposite directions are equal in length, showing that they cancel.

P2.2i Apply Newton's Second Law in calculations relating forces, masses and accelerations

1.

State the equation linking force, mass and acceleration.

resultant force = mass × acceleration.

2.

A 5 kg object accelerates at 4 m/s². Calculate the resultant force.

Force = 5 × 4 = 20 N.

3.

A force of 36 N acts on an object with a mass of 9 kg. Calculate its acceleration.

Acceleration = 36 / 9 = 4 m/s².

4.

A force of 50 N produces an acceleration of 10 m/s². Calculate the mass of the object.

Mass = 50 / 10 = 5 kg.

5.

Explain how increasing the mass affects the acceleration when the force remains constant.

For a constant force, increasing the mass decreases the acceleration.

6.

Explain why a larger resultant force produces a greater acceleration for the same mass.

For the same mass, a larger resultant force produces a proportionally greater acceleration.

P2.2j Explain that inertia is a measure of how difficult it is to change the velocity of an object and that the inertial mass is defined as the ratio of force over acceleration

1.

What is meant by inertia?

Inertia is the tendency of an object to resist a change in its velocity.

2.

Which object has greater inertia: a car or a bicycle?

A car.

3.

Why is it more difficult to accelerate a lorry than a car?

A lorry has a greater mass and therefore greater inertia, so a larger force is required to produce the same acceleration.

4.

What is meant by inertial mass?

Inertial mass is a measure of how difficult it is to change an object's velocity.

5.

State the relationship between inertial mass, force and acceleration.

inertial mass = force / acceleration.

6.

Explain why objects with greater mass have greater inertia.

Objects with greater mass resist changes in motion more strongly, so they have greater inertia.

P2.2k Define momentum and describe examples of momentum in collisions

1.

What is momentum?

Momentum is a measure of an object's motion and depends on its mass and velocity.

2.

State the equation used to calculate momentum.

momentum = mass × velocity.

3.

What are the units of momentum?

kg m/s.

4.

Explain what happens to momentum during a collision in a closed system.

The total momentum before the collision equals the total momentum after the collision.

5.

Give an example of momentum in a road traffic collision.

During a car collision, the vehicles exchange momentum and may change speed or direction.

6.

Describe the law of conservation of momentum.

In a closed system, the total momentum remains constant, provided no external resultant force acts.

P2.2l Apply formulae relating force, mass, velocity and acceleration to explain how the changes involved are inter-related

1.

State the equation linking force, mass and acceleration.

force = mass × acceleration.

2.

State the equation linking momentum, mass and velocity.

momentum = mass × velocity.

3.

A 4 kg object accelerates at 3 m/s². Calculate the resultant force.

Force = 4 × 3 = 12 N.

4.

A 6 kg object travels at 5 m/s. Calculate its momentum.

Momentum = 6 × 5 = 30 kg m/s.

5.

Explain how increasing the force affects the acceleration of an object with constant mass.

Increasing the force increases the acceleration in direct proportion when mass remains constant.

6.

Explain how increasing the mass affects both acceleration and momentum.

Increasing mass reduces acceleration for the same force, but increases momentum for the same velocity.

P2.2m Use the relationship between work done, force, and distance moved along the line of action of the force and describe the energy transfer involved

1.

State the equation linking work done, force and distance.

work done = force × distance moved in the direction of the force.

2.

What are the units of work done?

Joules (J).

3.

A force of 20 N moves an object 5 m. Calculate the work done.

Work done = 20 × 5 = 100 J.

4.

Describe the energy transfer when work is done lifting an object.

Energy is transferred mechanically to the object's gravitational potential energy store.

5.

Explain what happens to the energy of an object when work is done against friction.

Energy is transferred from the object's energy stores to the thermal energy stores of the object and surroundings.

6.

Explain why work done is equal to the energy transferred.

Work done measures the energy transferred when a force moves an object through a distance.

P2.2n Calculate relevant values of stored energy and energy transfers; convert between newton-metres and joules

1.

What is the SI unit of energy?

Joule (J).

2.

How many joules are equal to 15 newton-metres?

15 J.

3.

How many newton-metres are equal to 250 J?

250 N m.

4.

A machine transfers 800 J of energy. State this value in newton-metres.

800 N m.

5.

Explain why 1 J is equal to 1 N m.

One joule is the work done when a force of 1 N moves an object 1 m in the direction of the force.

6.

Describe how energy is transferred when work is done.

A force does work by moving an object, transferring energy between stores.

P2.2o Explain, with reference to examples, the definition of power as the rate at which energy is transferred

1.

What is power?

Power is the rate at which energy is transferred or work is done.

2.

State the equation linking power, energy transferred and time.

power = energy transferred / time.

3.

What is the unit of power?

Watt (W).

4.

A motor transfers 1200 J of energy in 60 s. Calculate its power.

Power = 1200 / 60 = 20 W.

5.

Explain why a more powerful kettle boils water more quickly.

A more powerful kettle transfers energy to the water at a greater rate, so the water reaches boiling temperature more quickly.

6.

Describe what is meant by the rate of energy transfer.

The rate of energy transfer is the amount of energy transferred each second.

P2.2p Recall and apply Newton's Third Law

1.

State Newton's Third Law.

When two objects interact, they exert equal and opposite forces on each other.

2.

What happens when one object exerts a force on another object?

The second object exerts an equal-sized force in the opposite direction on the first object.

3.

Give an example of Newton's Third Law involving walking.

A person pushes backwards on the ground, and the ground pushes the person forwards with an equal and opposite force.

4.

Explain how a rocket launches using Newton's Third Law.

The rocket pushes exhaust gases downwards, and the gases exert an equal and opposite upward force on the rocket.

5.

Describe the action and reaction forces when a swimmer pushes against the water.

The swimmer pushes the water backwards, and the water pushes the swimmer forwards with an equal and opposite force.

6.

Explain why action and reaction forces do not cancel each other out.

They do not cancel because they act on different objects.

P2.2q Explain why an object moving in a circle with a constant speed has a changing velocity (qualitative only)

1.

Why does an object moving in a circle have a changing velocity?

Its direction of motion continuously changes, so its velocity changes.

2.

What happens to the direction of velocity during circular motion?

The direction of velocity changes continuously and is always tangential to the circular path.

3.

Does the speed of an object moving in a circle at constant speed change?

No. Its speed remains constant.

4.

Explain why velocity is a vector quantity.

Velocity is a vector quantity because it has both magnitude and direction.

5.

Give an example of an object moving with constant speed in a circle.

A satellite orbiting the Earth.

6.

Explain why an object moving in a circle is accelerating even when its speed remains constant.

Acceleration is the rate of change of velocity. The direction of velocity changes continuously, so the object is accelerating even though its speed remains constant.

P2.3a Explain that to stretch, bend or compress an object, more than one force has to be applied

1.

What must happen to stretch an object?

Two forces must act in opposite directions to pull the object apart.

2.

What must happen to compress an object?

Two forces must act towards each other to push the object together.

3.

Why can't a single force acting alone stretch a spring?

A single force would usually move or accelerate the whole spring rather than change its shape.

4.

Describe the forces acting when a rubber band is stretched.

Opposing forces pull on each end of the rubber band.

5.

Explain why bending an object requires more than one force.

Bending requires forces acting in different directions or at different points so that different parts of the object move differently.

6.

Give an everyday example where two or more forces stretch, bend or compress an object.

Stretching a spring, bending a ruler or compressing a sponge using forces on opposite sides.

P2.3b Describe the difference between elastic and plastic deformation (distortions) caused by stretching forces

1.

What is elastic deformation?

Elastic deformation is a temporary change of shape that is reversed when the force is removed.

2.

What is plastic deformation?

Plastic deformation is a permanent change of shape that remains after the force is removed.

3.

What happens to an object after elastic deformation when the force is removed?

It returns to its original shape and size.

4.

What happens to an object after plastic deformation when the force is removed?

It remains permanently deformed.

5.

Give an example of a material that shows elastic deformation.

A spring or rubber band, provided its elastic limit is not exceeded.

6.

Compare elastic deformation with plastic deformation.

Elastic deformation is reversible, whereas plastic deformation is permanent.

P2.3c Describe the relationship between force and extension for a spring and other simple systems

1.

What happens to the extension of a spring as the force increases?

The extension increases as the applied force increases.

2.

What is meant by the extension of a spring?

Extension is the increase in length from the spring's original length.

3.

State the relationship between force and extension before the limit of proportionality.

Force is directly proportional to extension.

4.

How is the relationship between force and extension shown on a graph?

It is shown by a straight line through the origin on a force-extension graph.

5.

Describe what happens to the spring when the force is removed before the elastic limit.

The spring returns to its original length.

6.

Explain the relationship between force and extension for a spring.

Before the limit of proportionality, doubling the force doubles the extension. Beyond this limit, the relationship is no longer directly proportional.

P2.3d Describe the difference between linear and non-linear relationships between force and extension

1.

What is a linear relationship?

A linear relationship is one in which one quantity is directly proportional to the other.

2.

What is a non-linear relationship?

A non-linear relationship is one in which the quantities are not directly proportional.

3.

What does a straight-line force-extension graph show?

Force is directly proportional to extension.

4.

What does a curved force-extension graph show?

The extension is no longer directly proportional to the force.

5.

Explain why the graph becomes non-linear after the limit of proportionality.

After the limit of proportionality, the material's behaviour changes and each additional increase in force produces a different increase in extension.

6.

Compare linear and non-linear force-extension graphs.

A linear graph is a straight line, usually through the origin, while a non-linear graph is curved.

P2.3e Calculate a spring constant in linear cases

1.

State the equation linking force, spring constant and extension.

force = spring constant × extension.

2.

What are the units of spring constant?

N/m.

3.

A spring extends 0.20 m when a force of 10 N is applied. Calculate the spring constant.

spring constant = 10 / 0.20 = 50 N/m.

4.

A spring has a spring constant of 400 N/m and extends by 0.05 m. Calculate the force applied.

force = 400 × 0.05 = 20 N.

5.

A force of 15 N stretches a spring with a spring constant of 300 N/m. Calculate the extension.

extension = 15 / 300 = 0.05 m.

6.

Explain what a large spring constant tells you about a spring.

A large spring constant means the spring is stiff and requires a large force to produce a small extension.

P2.3f Calculate the work done in stretching

1.

What is meant by work done?

Work done is the energy transferred when a force moves through a distance.

2.

State the equation used to calculate the work done in stretching a spring.

work done = 0.5 × force × extension.

3.

Calculate the work done when a 12 N force stretches a spring by 0.30 m.

work done = 0.5 × 12 × 0.30 = 1.8 J.

4.

A spring stores 8 J of energy when stretched. State the work done.

8 J.

5.

Explain where the energy is stored when a spring is stretched.

It is stored in the elastic potential energy store of the spring.

6.

Describe the relationship between work done and elastic potential energy.

The work done in stretching the spring is equal to the elastic potential energy stored, provided no energy is dissipated.

P2.3g Describe that all matter has a gravitational field that causes attraction, and the field strength is much greater for massive objects

1.

What is a gravitational field?

A gravitational field is a region in which a mass experiences a gravitational force.

2.

Why do all objects attract each other gravitationally?

All matter has mass, and masses attract each other gravitationally.

3.

Which objects produce the strongest gravitational fields?

Objects with very large masses, such as planets and stars.

4.

Why does the Earth have a much stronger gravitational field than the Moon?

The Earth has much greater mass than the Moon.

5.

Explain how mass affects gravitational field strength.

Greater mass produces a stronger gravitational field.

6.

Describe the relationship between mass and gravitational attraction.

Increasing the mass of an object increases the gravitational attraction it exerts on other objects.

P2.3h Define weight, describe how it is measured and describe the relationship between the weight of an object and the gravitational field strength, g

1.

What is weight?

Weight is the force acting on an object due to gravity.

2.

What instrument is used to measure weight?

A newton meter or force meter.

3.

What are the units of weight?

Newtons (N).

4.

State the equation linking weight, mass and gravitational field strength.

weight = mass × gravitational field strength.

5.

What is the value of gravitational field strength on Earth?

Approximately 10 N/kg.

6.

Explain how the weight of an object changes on different planets.

The mass remains the same, but the weight changes because gravitational field strength is different on different planets.

P2.3i Recall the acceleration in free fall

1.

What is meant by free fall?

Free fall is motion under the influence of gravity alone.

2.

What is the acceleration due to gravity on Earth?

Approximately 9.8 m/s², often taken as 10 m/s².

3.

Why do objects accelerate during free fall?

A resultant gravitational force acts on them.

4.

What force causes free fall?

Gravity.

5.

Explain why objects in free fall accelerate at the same rate when air resistance is negligible.

Gravitational acceleration does not depend on the object's mass when air resistance is negligible.

6.

Describe what happens to the speed of an object during free fall.

Its speed increases as it accelerates towards the Earth.

P2.3j Apply formulae relating force, mass and relevant physical constants, including gravitational field strength, g, to explore how changes in these are inter-related

1.

State the equation linking weight, mass and gravitational field strength.

weight = mass × gravitational field strength.

2.

Calculate the weight of a 5 kg object on Earth.

weight = 5 × 10 = 50 N.

3.

Calculate the mass of an object with a weight of 120 N on Earth.

mass = 120 / 10 = 12 kg.

4.

Explain how weight changes if gravitational field strength increases.

Weight increases in direct proportion to gravitational field strength.

5.

Explain why an object's mass remains constant when it is taken to another planet.

Mass is the amount of matter in the object and does not depend on location.

6.

Compare the weight of the same object on Earth and the Moon.

The object weighs more on Earth because Earth's gravitational field strength is greater than the Moon's, but its mass is unchanged.

P2.3k Describe examples in which forces cause rotation

1.

What is meant by rotation?

Rotation is the turning of an object about a pivot or axis.

2.

What is a pivot?

A pivot is the fixed point about which an object turns.

3.

Give an example of a force causing rotation.

Pushing down on the handle of a door causes it to rotate about its hinges.

4.

What determines whether an object rotates clockwise or anticlockwise?

It depends on the direction of the force and the side of the pivot on which it acts.

5.

Explain why pushing a door near its handle makes it easier to open.

The handle is further from the pivot, producing a greater turning effect for the same force.

6.

Describe how forces produce a turning effect.

A force acting at a distance from a pivot produces a turning effect called a moment.

P2.3l Define and calculate the moment of a force

1.

What is meant by the moment of a force?

The moment of a force is its turning effect about a pivot.

2.

State the equation used to calculate a moment.

moment = force × perpendicular distance from the pivot.

3.

What are the units of moment?

N m.

4.

Calculate the moment produced by a 20 N force acting 0.5 m from a pivot.

moment = 20 × 0.5 = 10 N m.

5.

Calculate the force needed to produce a moment of 15 Nm at a distance of 0.3 m.

force = 15 / 0.3 = 50 N.

6.

Explain the principle of moments for a balanced object.

For a balanced object, the total clockwise moment equals the total anticlockwise moment.

P2.3m Explain how levers and gears transmit the rotational effects of forces

1.

What is a lever?

A lever is a rigid bar that turns about a pivot.

2.

What is the purpose of a gear?

A gear transmits rotational motion and turning forces between rotating shafts.

3.

How can a lever act as a force multiplier?

Applying a force further from the pivot produces a larger moment, allowing a smaller force to move a larger load.

4.

Why are gears of different sizes used together?

Different-sized gears can change the speed, direction and turning force of rotation.

5.

Explain how gears change rotational speed.

A small gear driving a larger gear reduces rotational speed, while a large gear driving a smaller gear increases rotational speed.

6.

Describe how levers and gears make work easier.

Levers can multiply forces, while gears can change rotational speed, direction and turning effect.

P2.3n Recall that the pressure in fluids (gases and liquids) causes a net force at right angles to any surface

1.

In which direction does fluid pressure act on a surface?

At right angles, or perpendicular, to the surface.

2.

Do gases exert pressure?

Yes.

3.

Do liquids exert pressure?

Yes.

4.

Why does pressure produce a force on the walls of a container?

Moving fluid particles collide with the walls and exert forces on them.

5.

Explain why fluid pressure acts in all directions.

Fluid particles move randomly and collide with surfaces from all directions.

6.

Describe how pressure in a fluid produces a net force on a surface.

Pressure acting over the area of a surface produces a force perpendicular to that surface.

P2.3o Use the relationship between the force, the pressure and the area in contact

1.

State the equation linking pressure, force and area.

pressure = force / area.

2.

What are the units of pressure?

Pascals (Pa), equivalent to N/m².

3.

Calculate the pressure produced by a force of 100 N acting on an area of 0.5 m².

pressure = 100 / 0.5 = 200 Pa.

4.

Calculate the force produced by a pressure of 5000 Pa acting over an area of 0.2 m².

force = 5000 × 0.2 = 1000 N.

5.

Explain why increasing the contact area reduces pressure.

The same force is spread over a larger area, so the force per unit area is smaller.

6.

Describe how a simple hydraulic system works using pressure.

A force applied to a small piston produces pressure in the fluid. This pressure is transmitted through the fluid and acts on a larger piston, producing a larger force because the larger piston has a greater area.

P3.1a Describe that charge is a property of all matter and that there are positive and negative charges

1.

What is meant by electric charge?

Electric charge is a property of matter that causes charged objects to exert forces on one another.

2.

State the two types of electric charge.

Positive charge and negative charge.

3.

What type of charge does a proton have?

Positive charge.

4.

What type of charge does an electron have?

Negative charge.

5.

Explain why most bodies have zero net charge.

Most bodies contain equal amounts of positive and negative charge, so the charges balance and the net charge is zero.

6.

A body contains equal numbers of positive and negative charges. State its overall charge.

The body is electrically neutral because its overall charge is zero.

P3.1b Describe the production of static electricity, and sparking, by rubbing surfaces, and evidence that charged objects exert forces of attraction or repulsion on one another when not in contact

1.

Describe how rubbing two insulating surfaces can produce static electricity.

Rubbing two insulating surfaces can transfer electrons from one material to the other, leaving both objects statically charged.

2.

State the type of material on which static charge can build up.

An insulating material.

3.

What happens when two objects with like charges are brought close together?

They repel each other.

4.

What happens when two objects with opposite charges are brought close together?

They attract each other.

5.

Explain how a spark can be produced between a charged object and another object.

A large potential difference can cause electrons to move suddenly through the air, producing a spark.

6.

Describe one experiment that provides evidence that charged objects exert forces when they are not touching.

Charge two insulating rods by rubbing them, suspend one rod and bring the other close without touching. The suspended rod moves because of attraction or repulsion, showing that charged objects exert forces at a distance.

P3.1c Explain how transfer of electrons between objects can explain the phenomena of static electricity

1.

Which subatomic particles are transferred when objects become statically charged?

Electrons.

2.

What charge does an object gain when it gains electrons?

Negative charge.

3.

What charge does an object gain when it loses electrons?

Positive charge.

4.

Explain why positive charge does not move between objects during static charging.

Protons are held securely inside atomic nuclei and cannot move easily between objects.

5.

Two insulating materials are rubbed together. Explain how they become oppositely charged.

Electrons transfer from one material to the other. The material gaining electrons becomes negatively charged, while the material losing electrons becomes positively charged.

6.

Explain static electricity in terms of the transfer of electrons between objects.

Static electricity is produced when electrons are transferred between objects. An excess of electrons produces a negative charge, while a shortage of electrons produces a positive charge.

P3.1d Explain the concept of an electric field and how it helps to explain the phenomena of static electricity

1.

What is an electric field?

An electric field is a region in which a charged object experiences an electric force.

2.

Where is an electric field found?

Around any electrically charged object.

3.

Explain how an electric field can exert a force on a charged object.

A charged object placed in the field experiences an attractive or repulsive force.

4.

How do electric fields help to explain attraction between opposite charges?

The electric field around one charge exerts an attractive force on an opposite charge placed within it.

5.

How do electric fields help to explain repulsion between like charges?

The electric field around one charge exerts a repulsive force on a like charge placed within it.

6.

Explain how two charged objects can exert forces on each other without being in contact.

Each charged object produces an electric field. When another charged object enters this field, it experiences a force even though the objects are not touching.

P3.1e Recall that current is a rate of flow of charge (electrons) and the conditions needed for charge to flow

1.

What is electric current?

Electric current is the rate at which electric charge flows.

2.

Which particles carry charge through a metal wire?

Electrons.

3.

State the two conditions needed for charge to flow through a circuit.

A closed circuit and a source of potential difference.

4.

Why is a source of potential difference needed for charge to flow?

The potential difference transfers energy to the charges and provides the push that causes them to move around the circuit.

5.

Why must a circuit be closed for current to flow?

A closed circuit provides a complete path through which charge can flow.

6.

Explain why no current flows when a switch in a circuit is open.

An open switch breaks the circuit, so there is no complete path for charge and no current flows.

P3.1f Recall that current has the same value at any point in a single closed loop

1.

State how the current changes around a single closed loop.

The current has the same value at every point in a single closed loop.

2.

A current of 0.4 A enters a lamp in a single closed loop. What current leaves the lamp?

0.4 A.

3.

Two ammeters are placed at different points in a single closed loop. Compare their readings.

The two ammeters have the same reading.

4.

Explain why charge does not become used up as it passes through a component.

Charge is transferred around the circuit but is conserved; components transfer energy from the charges rather than using up the charge itself.

5.

A current of 2.5 A passes through a battery in a single closed loop. State the current through every other point in the loop.

2.5 A.

6.

Describe the current at different points in a series circuit containing a cell and two resistors.

The current through the cell, both resistors and every other point in the series circuit is the same.

P3.1g Recall and use the relationship between quantity of charge, current and time

1.

State the equation linking quantity of charge, current and time.

charge = current × time.

2.

State the unit used to measure quantity of charge.

Coulomb (C).

3.

Calculate the charge transferred when a current of 3 A flows for 20 s.

Charge = 3 × 20 = 60 C.

4.

Calculate the current when 240 C of charge flows in 80 s.

Current = 240 ÷ 80 = 3 A.

5.

Calculate the time taken for 500 C of charge to flow at a current of 4 A.

Time = 500 ÷ 4 = 125 s.

6.

A current increases while the time remains constant. Explain how this affects the quantity of charge transferred.

The quantity of charge transferred increases because charge is directly proportional to current when time remains constant.

P3.2a Describe the differences between series and parallel circuits

1.

What is meant by a series circuit?

A series circuit has all components connected in a single loop, so there is only one path for the current.

2.

What is meant by a parallel circuit?

A parallel circuit has components connected on separate branches, providing more than one path for the current.

3.

Compare the current in series and parallel circuits.

In a series circuit the current is the same through every component. In a parallel circuit the current splits between the branches.

4.

Compare the potential difference in series and parallel circuits.

In a series circuit the supply potential difference is shared between the components. In a parallel circuit the potential difference across each branch is the same as the supply.

5.

Where should an ammeter be positioned in a circuit?

An ammeter should be connected in series with the component.

6.

Where should a voltmeter be positioned in a circuit?

A voltmeter should be connected in parallel across the component.

P3.2b Represent d.c. circuits with the conventions of positive and negative terminals, and the symbols that represent common circuit elements

1.

Draw the circuit symbol for a cell.

The standard circuit symbol for a cell (one long line and one short line).

2.

Draw the circuit symbol for an ammeter.

The standard circuit symbol for an ammeter (a circle containing A).

3.

Draw the circuit symbol for a voltmeter.

The standard circuit symbol for a voltmeter (a circle containing V).

4.

Draw the circuit symbols for a fixed resistor and a variable resistor.

The standard circuit symbols for a fixed resistor and a variable resistor.

5.

Draw the circuit symbols for a diode, filament lamp, LDR and NTC thermistor.

The standard circuit symbols for a diode, filament lamp, LDR and NTC thermistor.

6.

Draw a circuit diagram containing a cell, switch, resistor and ammeter, showing the positive and negative terminals correctly.

A correctly drawn circuit containing a cell, switch, resistor and ammeter in series, with the positive and negative terminals of the cell shown correctly.

P3.2c Recall that current, I, depends on both resistance, R, and potential difference, V, and the units in which these are measured

1.

What is the symbol used for current?

I.

2.

State the unit used to measure current.

Ampere (A).

3.

State the unit used to measure resistance.

Ohm (Ω).

4.

State the unit used to measure potential difference.

Volt (V).

5.

Define potential difference.

Potential difference is the energy transferred per unit charge between two points in a circuit.

6.

Describe how changing resistance or potential difference can affect the current in a circuit.

Increasing the potential difference increases the current, while increasing the resistance decreases the current.

P3.2d Recall and apply the relationship between I, R and V, and that for some resistors the value of R remains constant but that in others it can change as the current changes

1.

State the equation linking potential difference, current and resistance.

potential difference = current × resistance (V = IR).

2.

Calculate the potential difference across a 6 Ω resistor carrying a current of 2 A.

Potential difference = 6 × 2 = 12 V.

3.

Calculate the current through a 20 Ω resistor connected across 10 V.

Current = 10 ÷ 20 = 0.5 A.

4.

Calculate the resistance of a component when the potential difference is 12 V and the current is 0.4 A.

Resistance = 12 ÷ 0.4 = 30 Ω.

5.

What is meant by a resistor having a constant resistance?

Its resistance does not change as the current changes, provided the temperature remains constant.

6.

Explain why the resistance of some components changes as the current changes.

As the current increases, some components become hotter, changing their resistance.

P3.2e Explain that for some resistors the value of R remains constant but that in others it can change as the current changes

1.

What happens to the resistance of an ohmic conductor when its current changes at constant temperature?

It remains constant if the temperature stays constant.

2.

Give an example of a component whose resistance changes as the current changes.

A filament lamp.

3.

Explain why the resistance of a filament lamp changes as the current increases.

As the filament becomes hotter, its resistance increases.

4.

Compare the resistance behaviour of a fixed resistor and a filament lamp.

A fixed resistor has a constant resistance, whereas a filament lamp's resistance increases as current increases.

5.

Explain why not all electrical components have a constant resistance.

Some components change temperature or respond to environmental conditions, causing their resistance to change.

6.

Describe how measurements of current and potential difference can be used to determine whether resistance is constant.

Measure the current and potential difference for different values and calculate the resistance using R = V/I. If the resistance stays the same it is constant; if it changes it is not constant.

P3.2f Explain the design and use of circuits to explore such effects

1.

Describe a circuit that could be used to investigate the resistance of a component.

Connect the component in series with an ammeter and a variable resistor, with a voltmeter connected across the component.

2.

Where should the ammeter be connected when investigating a component?

In series with the component.

3.

Where should the voltmeter be connected when investigating a component?

In parallel across the component.

4.

Explain how a variable resistor can be used to change the current in an investigation.

Adjusting the variable resistor changes the current flowing through the circuit.

5.

Describe how you could investigate the current and potential difference for a filament lamp.

Use the circuit to take pairs of current and potential difference readings while changing the current with a variable resistor.

6.

Explain how circuits can be used to investigate wires, diodes, NTC thermistors and LDRs.

Use the same circuit arrangement, replacing the test component with the wire, diode, thermistor or LDR, and measure current and potential difference over a range of values.

P3.2g Use graphs to explore whether circuit elements are linear or non-linear

1.

What is meant by a linear circuit element?

A component whose current is directly proportional to potential difference.

2.

What is meant by a non-linear circuit element?

A component whose current is not directly proportional to potential difference.

3.

What shape of current-potential difference graph would indicate a linear relationship?

A straight line through the origin.

4.

How can a graph be used to identify a non-linear circuit element?

Its current-potential difference graph is curved.

5.

A resistor produces a straight-line current-potential difference graph through the origin. What does this show?

It shows that the resistance remains constant.

6.

Compare the current-potential difference graphs of linear and non-linear components.

Linear components produce a straight-line graph, while non-linear components produce a curved graph.

P3.2h Use graphs and relate the curves produced to the function and properties of circuit elements

1.

Describe the shape of the current-potential difference graph for a fixed resistor at constant temperature.

A straight line through the origin.

2.

Describe the shape of the current-potential difference graph for a filament lamp.

A curve that becomes less steep as potential difference increases.

3.

Describe the current-potential difference graph for a diode.

Almost no current flows in one direction until the threshold is reached; in the opposite direction virtually no current flows.

4.

Explain what the graph for a filament lamp shows about its resistance.

As current increases, the filament becomes hotter and its resistance increases.

5.

Explain what the graph for a diode shows about the direction in which it conducts current.

It shows that current flows easily in only one direction.

6.

Use the shape of a current-potential difference graph to identify whether a component could be a resistor, filament lamp or diode.

A straight-line graph indicates a fixed resistor, a curved symmetrical graph indicates a filament lamp, and a graph with current mainly in one direction indicates a diode.

P3.2i Explain why, if two resistors are in series the net resistance is increased, whereas with two in parallel the net resistance is decreased (qualitative explanation only)

1.

What happens to the total resistance when another resistor is added in series?

The total resistance increases.

2.

What happens to the total resistance when another resistor is added in parallel?

The total resistance decreases.

3.

Explain why two resistors in series have a greater net resistance than either resistor alone.

The current must pass through both resistors, so both oppose the flow of charge.

4.

Explain why adding another parallel branch decreases the net resistance.

Adding another branch provides an extra path for current, reducing the overall resistance.

5.

Compare the net resistance of two resistors connected in series with the same resistors connected in parallel.

The series combination has a greater total resistance than the parallel combination.

6.

Explain qualitatively how the number of available paths for current affects the net resistance.

More available paths allow current to flow more easily, reducing the equivalent resistance.

P3.2j Calculate the currents, potential differences and resistances in d.c. series and parallel circuits

1.

Two resistors of 4 Ω and 6 Ω are connected in series. Calculate their total resistance.

Total resistance = 4 + 6 = 10 Ω.

2.

A 12 V supply is connected to a series circuit with a total resistance of 6 Ω. Calculate the current.

Current = 12 ÷ 6 = 2 A.

3.

Two identical parallel branches each carry a current of 0.5 A. Calculate the total current from the supply.

Total current = 0.5 + 0.5 = 1.0 A.

4.

A resistor has a potential difference of 8 V and carries a current of 2 A. Calculate its resistance.

Resistance = 8 ÷ 2 = 4 Ω.

5.

Calculate the potential difference across a 10 Ω resistor carrying a current of 0.3 A.

Potential difference = 10 × 0.3 = 3 V.

6.

Explain how current and potential difference are distributed in series and parallel circuits.

In a series circuit the current is the same throughout and the potential difference is shared. In a parallel circuit the potential difference is the same across each branch and the current splits between the branches.

P3.2k Explain the design and use of d.c. circuits for measurement and testing purposes

1.

Explain how an ammeter should be connected to measure the current through a component.

Connect the ammeter in series with the component.

2.

Explain how a voltmeter should be connected to measure the potential difference across a component.

Connect the voltmeter in parallel across the component.

3.

Describe how a circuit could be designed to measure the resistance of a resistor.

Measure the current and potential difference, then calculate the resistance using R = V/I.

4.

Explain how a variable resistor can be used when testing an electrical component.

It allows the current in the circuit to be varied.

5.

Describe how a d.c. circuit could be used to test the behaviour of an LDR.

Place the LDR in the circuit and measure how current and potential difference change as the light intensity changes.

6.

Describe how a d.c. circuit could be used to test the behaviour of an NTC thermistor.

Place the thermistor in the circuit and measure how current and potential difference change as its temperature changes.

P3.2l Explain how the power transfer in any circuit device is related to the potential difference across it and the current, and to the energy changes over a given time

1.

State the equation linking power, potential difference and current.

power = potential difference × current (P = VI).

2.

What is meant by electrical power?

Electrical power is the rate at which electrical energy is transferred.

3.

Calculate the power of a device operating at 12 V with a current of 3 A.

Power = 12 × 3 = 36 W.

4.

A device transfers 600 J of energy in 20 s. Calculate its power.

Power = 600 ÷ 20 = 30 W.

5.

Explain how increasing the potential difference can affect the power transferred by a device.

If the current also increases, increasing the potential difference increases the power transferred.

6.

Explain the relationship between power, energy transferred and time.

Power is the rate of energy transfer, so power = energy transferred ÷ time.

P3.2m Apply the equations relating potential difference, current, quantity of charge, resistance, power, energy, and time, and solve problems for circuits which include resistors in series, using the concept of equivalent resistance

1.

A current of 2 A flows for 40 s. Calculate the charge transferred.

Charge = 2 × 40 = 80 C.

2.

A 12 V supply produces a current of 3 A through a resistor. Calculate the resistance.

Resistance = 12 ÷ 3 = 4 Ω.

3.

A device operates at 6 V and draws a current of 4 A. Calculate its power.

Power = 6 × 4 = 24 W.

4.

A 50 W device operates for 30 s. Calculate the energy transferred.

Energy = 50 × 30 = 1500 J.

5.

Two resistors of 5 Ω and 7 Ω are connected in series. Calculate their equivalent resistance and the current when connected to a 24 V supply.

Equivalent resistance = 5 + 7 = 12 Ω. Current = 24 ÷ 12 = 2 A.

6.

A charge of 120 C passes through a component with a potential difference of 10 V. Calculate the energy transferred.

Energy transferred = charge × potential difference = 120 × 10 = 1200 J.

P4.1a Describe the attraction and repulsion between unlike and like poles for permanent magnets

1.

What happens when two north poles are brought close together?

They repel each other.

2.

What happens when two south poles are brought close together?

They repel each other.

3.

What happens when a north pole is brought close to a south pole?

They attract each other.

4.

State the rule for the interaction between like magnetic poles.

Like magnetic poles repel.

5.

State the rule for the interaction between unlike magnetic poles.

Unlike magnetic poles attract.

6.

Sketch the magnetic field pattern between two bar magnets positioned so that they attract each other.

The magnetic field lines join from the north pole of one magnet to the south pole of the other, showing attraction.

P4.1b Describe the difference between permanent and induced magnets

1.

What is a permanent magnet?

A magnet that produces its own magnetic field and remains magnetised.

2.

What is an induced magnet?

A material that becomes magnetised only when placed in a magnetic field.

3.

What happens to an induced magnet when it is removed from a magnetic field?

It usually loses its magnetism.

4.

Compare the magnetic properties of permanent and induced magnets.

Permanent magnets remain magnetised, whereas induced magnets are only magnetic while in an external magnetic field.

5.

Explain how an unmagnetised magnetic material can become an induced magnet.

The external magnetic field aligns magnetic domains, causing the material to become magnetised.

6.

Describe one situation in which induced magnetism occurs.

A paperclip becoming magnetic when placed next to a bar magnet.

P4.1c Describe the characteristics of the magnetic field of a magnet, showing how strength and direction change from one point to another

1.

What is meant by a magnetic field?

The region around a magnet where another magnet or magnetic material experiences a force.

2.

In which direction do magnetic field lines point outside a bar magnet?

From the north pole to the south pole.

3.

Where is the magnetic field around a bar magnet strongest?

At the poles of the magnet.

4.

How does the spacing of magnetic field lines indicate the strength of the field?

The closer the field lines, the stronger the magnetic field.

5.

Describe how a plotting compass can be used to determine the direction of a magnetic field.

Move the plotting compass around the magnet and mark the direction the needle points at different positions.

6.

Sketch the magnetic field pattern around a bar magnet and indicate its direction.

Draw field lines leaving the north pole and entering the south pole, with arrows showing the direction from north to south and the lines closest together near the poles.

P4.1d Explain how the behaviour of a magnetic (dipping) compass is related to evidence that the core of the Earth must be magnetic

1.

What happens to a compass needle when it is free to rotate?

It aligns with the Earth's magnetic field.

2.

Why does a compass needle point approximately north-south?

Because the Earth acts like a giant magnet.

3.

What does the behaviour of a compass show about the Earth?

The Earth has a magnetic field.

4.

What is a dipping compass?

A compass that can rotate vertically as well as horizontally.

5.

Explain how a dipping compass provides evidence for the Earth's magnetic field.

It shows that the Earth's magnetic field has both horizontal and vertical components.

6.

Explain why the behaviour of magnetic compasses provides evidence that the core of the Earth must be magnetic.

Since compasses consistently align with the Earth's magnetic field, this provides evidence that the Earth's core produces a magnetic field.

P4.1e Describe how to show that a current can create a magnetic effect and describe the directions of the magnetic field around a conducting wire

1.

Describe an experiment that shows a current-carrying wire produces a magnetic field.

Place a straight wire through a card, connect it to a power supply and sprinkle iron filings or use plotting compasses around the wire.

2.

What happens to a plotting compass placed near a wire when current flows through the wire?

The compass needle deflects.

3.

Describe the shape of the magnetic field around a straight current-carrying wire.

Concentric circles around the wire.

4.

How can the direction of the magnetic field around a conducting wire be determined?

Use the right-hand grip rule.

5.

What happens to the direction of the magnetic field if the direction of the current is reversed?

The direction of the magnetic field reverses.

6.

Describe how plotting compasses can be used to map the magnetic field around a current-carrying wire.

Place plotting compasses around the wire and record the direction each compass points to map the circular magnetic field.

P4.1f Recall that the strength of the field depends on the current and the distance from the conductor

1.

What happens to the magnetic field strength when the current in a conductor increases?

It increases.

2.

What happens to the magnetic field strength as the distance from the conductor increases?

It decreases.

3.

A current through a wire is doubled. State how this affects the magnetic field around the wire.

The magnetic field becomes stronger.

4.

Compare the magnetic field strength at a point close to a conducting wire with a point further away.

The field is stronger close to the wire than further away.

5.

State the two factors that affect the strength of the magnetic field around a current-carrying conductor.

The current and the distance from the conductor.

6.

Explain how you could increase the magnetic field strength at a fixed distance from a conducting wire.

Increase the current flowing through the wire.

P4.1g Explain how solenoid arrangements can enhance the magnetic effect

1.

What is a solenoid?

A coil of wire.

2.

Describe the magnetic field produced by a current-carrying solenoid.

A magnetic field similar to that of a bar magnet.

3.

How does increasing the current through a solenoid affect its magnetic effect?

The magnetic field becomes stronger.

4.

How can increasing the number of turns in a solenoid affect its magnetic field?

The magnetic field becomes stronger.

5.

Explain why coiling a wire into a solenoid produces a stronger magnetic effect than a single straight wire.

The magnetic fields from each turn of the coil combine, producing a much stronger overall field.

6.

Describe how the magnetic effect of a solenoid can be increased.

Increase the current, increase the number of turns of the coil, or add a soft iron core.

P4.2a Describe how a magnet and a current-carrying conductor exert a force on one another

1.

What happens when a current-carrying conductor is placed in a magnetic field?

A force acts on the conductor.

2.

What two fields interact to produce a force on a current-carrying conductor?

The magnetic field of the magnet and the magnetic field around the current-carrying conductor.

3.

What happens to the force if the direction of the current is reversed?

The direction of the force reverses.

4.

What happens to the force if the direction of the magnetic field is reversed?

The direction of the force reverses.

5.

Describe the force exerted between a magnet and a current-carrying conductor.

A current-carrying conductor experiences a force at right angles to both the current and the magnetic field.

6.

Describe an experiment that demonstrates the force acting on a current-carrying conductor in a magnetic field.

Place a current-carrying wire between the poles of a magnet. When the current flows, the wire moves because a force acts on it.

P4.2b Show that Fleming's left-hand rule represents the relative orientations of the force, the current and the magnetic field

1.

What is Fleming's left-hand rule used to determine?

To determine the direction of the force on a current-carrying conductor in a magnetic field.

2.

Which finger represents the magnetic field in Fleming's left-hand rule?

First finger = magnetic field.

3.

Which finger represents the current in Fleming's left-hand rule?

Second (middle) finger = current.

4.

Which finger represents the force in Fleming's left-hand rule?

Thumb = force (motion).

5.

What is the angle between the force, current and magnetic field when Fleming's left-hand rule is applied?

The force, current and magnetic field are all at right angles (90°) to each other.

6.

Use Fleming's left-hand rule to determine the direction of the force when the directions of the current and magnetic field are given.

Point the first finger in the direction of the magnetic field and the second finger in the direction of the current; the thumb then shows the direction of the force.

P4.2c Apply the equation that links the force on a conductor to the magnetic flux density, the current and the length of conductor to calculate the forces involved

1.

State the equation linking force, magnetic flux density, current and length of conductor.

F = B × I × L.

2.

State the unit of magnetic flux density.

Tesla (T).

3.

Calculate the force on a 0.5 m conductor carrying a current of 4 A at right angles to a magnetic field of flux density 0.2 T.

F = B × I × L = 0.2 × 4 × 0.5 = 0.4 N.

4.

Calculate the magnetic flux density when a 0.4 m conductor carrying 5 A experiences a force of 0.6 N.

B = F ÷ (I × L) = 0.6 ÷ (5 × 0.4) = 0.3 T.

5.

Calculate the current required for a 0.25 m conductor in a 0.8 T magnetic field to experience a force of 1 N.

I = F ÷ (B × L) = 1 ÷ (0.8 × 0.25) = 5 A.

6.

Explain how increasing the current or length of conductor in the magnetic field affects the force.

Increasing the current or the length of conductor in the magnetic field increases the force acting on the conductor.

P4.2d Explain how the force exerted from a magnet and a current-carrying conductor is used to cause rotation in electric motors

1.

What causes a force to act on a current-carrying coil in an electric motor?

The interaction between the magnetic field and the current-carrying coil.

2.

Why do the forces on opposite sides of a current-carrying coil act in opposite directions?

The current flows in opposite directions on opposite sides of the coil.

3.

How do these forces cause the coil to rotate?

They create a turning moment that rotates the coil.

4.

What happens to the direction of rotation if the current is reversed?

The direction of rotation reverses.

5.

What happens to the direction of rotation if the magnetic field is reversed?

The direction of rotation reverses.

6.

Explain how the interaction between a magnetic field and a current-carrying conductor causes rotation in an electric motor.

Opposite forces act on each side of the current-carrying coil, producing a turning effect that causes continuous rotation in an electric motor.

P4.2e Recall that a change in the magnetic field around a conductor can give rise to an induced potential difference across its ends, which could drive a current, generating a magnetic field that would oppose the original change

1.

What can be induced across a conductor when the magnetic field around it changes?

A potential difference.

2.

What can an induced potential difference cause if the conductor forms part of a complete circuit?

An induced current.

3.

How can a magnet and conductor be moved to produce an induced potential difference?

Move the magnet relative to the conductor, or move the conductor through the magnetic field.

4.

What happens to the induced potential difference if the magnetic field changes more rapidly?

The induced potential difference increases.

5.

What magnetic field is produced when an induced current flows?

A magnetic field that opposes the original change.

6.

Explain how the magnetic field produced by an induced current opposes the original change that produced it.

The induced current produces its own magnetic field, which opposes the change in magnetic field that caused the induction (Lenz's Law).

P4.2f Explain how this effect is used in an alternator to generate a.c., and in a dynamo to generate d.c.

1.

What type of current is generated by an alternator?

Alternating current (a.c.).

2.

What type of current is generated by a dynamo?

Direct current (d.c.).

3.

How does electromagnetic induction allow an alternator to generate a potential difference?

Rotating a coil in a magnetic field changes the magnetic field through the coil, inducing a potential difference.

4.

Why does an alternator produce an alternating current?

The induced potential difference repeatedly reverses direction as the coil rotates.

5.

How does a dynamo produce a direct current?

A split-ring commutator reverses the connections every half turn to produce a direct current.

6.

Compare the electrical outputs of an alternator and a dynamo.

An alternator produces alternating current, whereas a dynamo produces direct current.

P4.2g Explain how the effect of an alternating current in one circuit, in inducing a current in another, is used in transformers

1.

What type of current must flow in the primary coil of a transformer?

Alternating current (a.c.).

2.

What happens to the magnetic field around the primary coil when an alternating current flows?

The magnetic field continually changes direction and strength.

3.

How does the changing magnetic field induce a potential difference in the secondary coil?

The changing magnetic field induces a potential difference in the secondary coil.

4.

Why would a steady direct current not continuously induce a potential difference in the secondary coil?

Because a steady magnetic field does not induce a continuous potential difference.

5.

What is the purpose of the iron core in a transformer?

To provide a path for the magnetic field between the coils.

6.

Explain how an alternating current in the primary circuit can induce a current in a separate secondary circuit.

The alternating current in the primary coil produces a changing magnetic field in the iron core, which induces a potential difference and current in the secondary coil.

P4.2h Explain how the ratio of the potential differences across the two coils in a transformer depends on the ratio of the numbers of turns in each

1.

What determines whether a transformer increases or decreases potential difference?

The ratio of the number of turns on the secondary coil to the number of turns on the primary coil.

2.

What is a step-up transformer?

A transformer that increases potential difference.

3.

What is a step-down transformer?

A transformer that decreases potential difference.

4.

What happens to the potential difference if the secondary coil has more turns than the primary coil?

The potential difference increases.

5.

What happens to the potential difference if the secondary coil has fewer turns than the primary coil?

The potential difference decreases.

6.

Explain the relationship between the ratio of potential differences and the ratio of the numbers of turns in a transformer.

Vp / Vs = Np / Ns.

P4.2i Apply the equations linking the potential differences and numbers of turns in the two coils of a transformer

1.

State the equation linking primary potential difference, secondary potential difference, primary turns and secondary turns.

Vp / Vs = Np / Ns.

2.

A transformer has 100 turns on the primary coil and 500 turns on the secondary coil. The primary potential difference is 12 V. Calculate the secondary potential difference.

Vs = (Ns ÷ Np) × Vp = (500 ÷ 100) × 12 = 60 V.

3.

A transformer has a primary potential difference of 230 V and a secondary potential difference of 23 V. The primary coil has 1000 turns. Calculate the number of turns on the secondary coil.

Ns = (Vs × Np) ÷ Vp = (23 × 1000) ÷ 230 = 100 turns.

4.

A transformer has 200 turns on its primary coil and 50 turns on its secondary coil. Calculate the secondary potential difference when the primary potential difference is 240 V.

Vs = (Ns ÷ Np) × Vp = (50 ÷ 200) × 240 = 60 V.

5.

A transformer produces 24 V from a 240 V supply. Calculate the ratio of secondary turns to primary turns.

Secondary turns : Primary turns = 24 : 240 = 1 : 10.

6.

Determine whether a transformer is step-up or step-down from given values of potential difference and number of turns.

A transformer is step-up if the secondary potential difference (and number of turns) is greater than the primary, and step-down if it is smaller.

P4.2j Explain the action of the microphone in converting the pressure variations in sound waves into variations in current in electrical circuits, and the reverse effect as used in loudspeakers and headphones

1.

What causes the diaphragm of a dynamic microphone to vibrate?

Sound waves.

2.

How does movement of the coil in a dynamic microphone produce an electrical signal?

The moving coil cuts magnetic field lines, inducing a potential difference.

3.

How do variations in sound pressure produce variations in current in a microphone circuit?

They cause the diaphragm and coil to vibrate, producing a varying current.

4.

What happens when a varying current passes through the coil of a loudspeaker?

The coil moves back and forth in the magnetic field.

5.

How does the movement of a loudspeaker cone produce sound waves?

The cone vibrates, producing sound waves in the air.

6.

Compare the energy transfers and processes occurring in a dynamic microphone and a loudspeaker.

A microphone converts sound energy into electrical energy by electromagnetic induction, while a loudspeaker converts electrical energy back into sound by using the force on a current-carrying coil in a magnetic field.

P5.1a Describe wave motion in terms of amplitude, wavelength, frequency and period

1.

What is the amplitude of a wave?

The maximum displacement of a point on a wave from its rest position.

2.

What is the wavelength of a wave?

The distance between two consecutive corresponding points on a wave (e.g. crest to crest).

3.

What is the frequency of a wave?

The number of complete waves passing a point each second.

4.

What is the period of a wave?

The time taken for one complete wave.

5.

How does increasing the amplitude change the appearance of a wave?

The wave becomes taller (greater maximum displacement from the rest position).

6.

Identify the amplitude and wavelength on a diagram of a wave.

Amplitude is the height from the rest position to a crest (or trough), and wavelength is the distance between two consecutive crests (or troughs).

P5.1b Define wavelength and frequency

1.

Define wavelength.

The distance between two corresponding points on successive waves.

2.

What is the unit of wavelength?

Metres (m).

3.

Define frequency.

The number of complete waves passing a point each second.

4.

What is the unit of frequency?

Hertz (Hz).

5.

What does a frequency of 50 Hz mean?

50 complete waves pass a point every second.

6.

Explain the difference between wavelength and frequency.

Wavelength is the length of one wave, whereas frequency is the number of waves passing a point each second.

P5.1c Describe and apply the relationship between wavelength, frequency and wave velocity

1.

State the relationship between wave velocity, frequency and wavelength.

Wave velocity = frequency × wavelength.

2.

What happens to wavelength if frequency increases while wave velocity remains constant?

The wavelength decreases.

3.

What happens to frequency if wavelength increases while wave velocity remains constant?

The frequency decreases.

4.

A wave has a frequency of 10 Hz and a wavelength of 2 m. Calculate its velocity.

Wave velocity = frequency × wavelength = 10 × 2 = 20 m/s.

5.

A wave travels at 300 m/s and has a frequency of 100 Hz. Calculate its wavelength.

Wavelength = wave velocity ÷ frequency = 300 ÷ 100 = 3 m.

6.

Explain the relationship between wavelength and frequency for waves travelling at constant velocity.

At constant wave velocity, wavelength and frequency are inversely proportional.

P5.1d Apply formulae relating velocity, frequency and wavelength

1.

State the equation linking wave velocity, frequency and wavelength.

Wave velocity = frequency × wavelength.

2.

Calculate the velocity of a wave with a frequency of 25 Hz and a wavelength of 4 m.

Wave velocity = 25 × 4 = 100 m/s.

3.

Calculate the frequency of a wave travelling at 600 m/s with a wavelength of 3 m.

Frequency = wave velocity ÷ wavelength = 600 ÷ 3 = 200 Hz.

4.

Calculate the wavelength of a wave travelling at 340 m/s with a frequency of 170 Hz.

Wavelength = wave velocity ÷ frequency = 340 ÷ 170 = 2 m.

5.

A wave has a wavelength of 0.5 m and travels at 20 m/s. Calculate its frequency.

Frequency = wave velocity ÷ wavelength = 20 ÷ 0.5 = 40 Hz.

6.

A wave has a frequency of 2.5 kHz and a wavelength of 0.12 m. Calculate its velocity in m/s.

Wave velocity = frequency × wavelength = 2500 × 0.12 = 300 m/s.

P5.1e Describe differences between transverse and longitudinal waves

1.

What is a transverse wave?

A wave in which the vibrations are perpendicular to the direction of travel.

2.

What is a longitudinal wave?

A wave in which the vibrations are parallel to the direction of travel.

3.

In which direction do particles vibrate in a transverse wave compared with the direction of wave travel?

Perpendicular to the direction of travel.

4.

In which direction do particles vibrate in a longitudinal wave compared with the direction of wave travel?

Parallel to the direction of travel.

5.

Give one example of a transverse wave and one example of a longitudinal wave.

Transverse: light wave. Longitudinal: sound wave.

6.

Compare the direction of vibration and direction of travel in transverse and longitudinal waves.

In transverse waves the vibrations are perpendicular to the direction of travel, whereas in longitudinal waves they are parallel.

P5.1f Show how changes, in velocity, frequency and wavelength, in transmission of sound waves from one medium to another, are inter-related

1.

What can happen to the velocity of a sound wave when it enters a different medium?

The velocity can increase or decrease.

2.

What happens to the frequency of a sound wave when it passes from one medium into another?

The frequency remains the same.

3.

What happens to the wavelength if the velocity changes but the frequency remains constant?

The wavelength changes.

4.

A sound wave slows down as it enters a different medium. Explain what happens to its wavelength.

The wavelength decreases because the velocity decreases while the frequency remains constant.

5.

A sound wave enters a medium in which it travels faster. Explain what happens to its wavelength.

The wavelength increases because the velocity increases while the frequency remains constant.

6.

Use the wave equation to explain how velocity, frequency and wavelength are related when sound passes from one medium to another.

Wave velocity = frequency × wavelength. Since the frequency stays constant when a sound wave enters a different medium, any change in velocity causes the wavelength to change proportionally.

P5.1g Describe the effects of reflection, transmission, and absorption of waves at material interfaces

1.

What is meant by reflection of a wave?

Reflection is when a wave bounces off a surface.

2.

What is meant by transmission of a wave?

Transmission is when a wave passes through a material.

3.

What is meant by absorption of a wave?

Absorption is when a material takes in the wave's energy.

4.

What can happen when a wave reaches the boundary between two materials?

It may be reflected, transmitted or absorbed.

5.

Explain how reflected ultrasound waves can be used to produce an image.

Reflected ultrasound waves are detected and used to create an image.

6.

Explain how reflection of sound waves is used in sonar.

Sound waves reflect from underwater objects and the reflected waves are used by sonar to determine their position.

P5.1h Describe, with examples, processes which convert wave disturbances between sound waves and vibrations in solids

1.

How can vibrations in a solid produce sound waves in air?

Vibrating the solid causes the surrounding air to vibrate, producing sound waves.

2.

How can sound waves in air cause a solid object to vibrate?

Sound waves make the solid vibrate.

3.

What happens to the eardrum when sound waves enter the ear?

The eardrum vibrates.

4.

How are vibrations transferred through the structures of the ear?

Vibrations pass through the ear bones to the inner ear.

5.

Explain how a loudspeaker converts vibrations of a solid into sound waves.

The loudspeaker cone vibrates, pushing and pulling the air to produce sound waves.

6.

Describe one process in which sound waves are converted into vibrations in a solid and one in which vibrations in a solid are converted into sound waves.

Sound waves can make the eardrum vibrate, while vibrations of a loudspeaker cone produce sound waves in the air.

P5.1i Explain why such processes only work over a limited frequency range, and the relevance of this to human hearing

1.

What is meant by the frequency range of human hearing?

The range of frequencies that humans can hear.

2.

Why can humans not hear every possible sound frequency?

The ear only responds to a limited range of frequencies.

3.

What is the approximate frequency range of normal human hearing?

Approximately 20 Hz to 20 000 Hz.

4.

Why are very high-frequency sounds inaudible to humans?

They are outside the hearing range of the human ear.

5.

How can ageing affect the range of frequencies a person can hear?

Ageing usually reduces the ability to hear high-frequency sounds.

6.

Explain why the conversion of sound waves into vibrations in the ear only works over a limited frequency range.

The ear can only convert sound waves into nerve signals over a limited range of frequencies, so sounds outside this range cannot be heard.

P5.1j Describe how ripples on water surfaces are used to model transverse waves whilst sound waves in air are longitudinal waves, and how the speed of each may be measured

1.

Why can ripples on a water surface be used to model transverse waves?

The vibrations are perpendicular to the direction the wave travels.

2.

Why are sound waves in air described as longitudinal waves?

The vibrations are parallel to the direction the wave travels.

3.

Describe how the speed of water waves can be measured using a ripple tank.

Measure the wavelength and frequency of the ripples, then calculate speed using: wave velocity = frequency × wavelength.

4.

Describe how the speed of sound in air can be measured.

Measure the distance travelled and the time taken, then calculate speed using: speed = distance ÷ time.

5.

What measurements are needed to calculate the speed of ripples on water?

Wavelength and frequency.

6.

Compare the particle vibrations in water surface waves with those in sound waves in air.

Water surface waves model transverse waves because the vibrations are perpendicular to the direction of travel, whereas sound waves are longitudinal because the vibrations are parallel.

P5.1k Describe evidence for the cases of ripples on water surfaces and for sound waves in air that it is the wave that travels and not the water or the air

1.

What travels through a medium when a wave passes through it?

Energy.

2.

Does the water itself travel across a ripple tank with the wave?

No.

3.

How can a floating object provide evidence that water particles do not travel with a water wave?

It bobs up and down but does not move across the tank with the wave.

4.

Do air particles travel from a sound source all the way to the listener?

No.

5.

Describe how air particles move as a sound wave passes through the air.

Air particles vibrate backwards and forwards about their fixed positions.

6.

Explain the evidence that waves transfer energy while the particles of the medium only oscillate about their positions.

Waves transfer energy through a medium while the particles of the medium only oscillate about their positions and do not travel with the wave.

P5.2a Recall that electromagnetic waves are transverse and are transmitted through space where all have the same velocity

1.

What type of waves are electromagnetic waves?

Transverse waves.

2.

Can electromagnetic waves travel through a vacuum?

Yes.

3.

What is the velocity of electromagnetic waves in a vacuum?

Approximately 3 × 10⁸ m/s.

4.

Compare the velocities of radio waves and gamma rays in a vacuum.

They travel at the same speed in a vacuum.

5.

Explain why electromagnetic waves can travel through space.

Electromagnetic waves do not require a medium, so they can travel through empty space.

6.

State two properties that all electromagnetic waves have in common.

All electromagnetic waves are transverse and travel through a vacuum at approximately 3 × 10⁸ m/s.

P5.2b Explain that electromagnetic waves transfer energy from source to absorber

1.

What do electromagnetic waves transfer?

Energy.

2.

Where does the energy carried by an electromagnetic wave originate?

The source emitting the electromagnetic wave.

3.

What happens to the energy when an electromagnetic wave is absorbed?

The energy is transferred to the absorber.

4.

Give an example of an electromagnetic wave transferring energy to an absorber.

Infrared radiation from a heater warms an object.

5.

Explain how infrared radiation can transfer energy from a source to an object.

Infrared radiation is absorbed by the object, increasing its internal energy.

6.

Describe the energy transfer that occurs when electromagnetic radiation is absorbed by matter.

When electromagnetic radiation is absorbed, its energy is transferred to the absorbing material.

P5.2c Apply the relationships between frequency and wavelength across the electromagnetic spectrum

1.

What happens to wavelength as frequency increases across the electromagnetic spectrum?

Wavelength decreases.

2.

Which electromagnetic waves have the longest wavelengths?

Radio waves.

3.

Which electromagnetic waves have the highest frequencies?

Gamma rays.

4.

Compare the wavelength and frequency of radio waves with gamma rays.

Radio waves have long wavelengths and low frequencies, whereas gamma rays have short wavelengths and high frequencies.

5.

Explain the relationship between frequency and wavelength for electromagnetic waves travelling at the same velocity.

At the same wave speed, frequency and wavelength are inversely proportional.

6.

Use the wave equation to explain why a shorter wavelength corresponds to a higher frequency.

Wave velocity = frequency × wavelength. Since all electromagnetic waves travel at the same speed in a vacuum, a shorter wavelength means a higher frequency.

P5.2d Describe the main groupings of the electromagnetic spectrum and that these groupings range from long to short wavelengths and from low to high frequencies

1.

List the seven main regions of the electromagnetic spectrum in order of increasing frequency.

Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.

2.

Which region of the electromagnetic spectrum has the longest wavelength?

Radio waves.

3.

Which region of the electromagnetic spectrum has the shortest wavelength?

Gamma rays.

4.

State the order of the colours of visible light from lowest to highest frequency.

Red, orange, yellow, green, blue, indigo, violet.

5.

Place microwaves, ultraviolet and infrared in order of increasing frequency.

Infrared, microwaves, ultraviolet.

6.

Describe how wavelength and frequency change from radio waves to gamma rays across the electromagnetic spectrum.

From radio waves to gamma rays, wavelength decreases while frequency increases.

P5.2e Describe that our eyes can only detect a limited range of the electromagnetic spectrum

1.

Which part of the electromagnetic spectrum can the human eye detect?

Visible light.

2.

Which colour of visible light has the longest wavelength?

Red.

3.

Which colour of visible light has the shortest wavelength?

Violet.

4.

Can the human eye directly detect infrared radiation?

No.

5.

Can the human eye directly detect ultraviolet radiation?

No.

6.

Explain what is meant by saying that visible light is only a limited range of the electromagnetic spectrum.

The human eye can only detect visible light, which is a small part of the electromagnetic spectrum.

P5.2f Recall that light is an electromagnetic wave

1.

What type of wave is visible light?

An electromagnetic wave.

2.

Is light a transverse or longitudinal wave?

Transverse.

3.

Can light travel through a vacuum?

Yes.

4.

What is the approximate speed of light in a vacuum?

Approximately 3 × 10⁸ m/s.

5.

State where visible light is found within the electromagnetic spectrum.

Between infrared and ultraviolet in the electromagnetic spectrum.

6.

State two properties that visible light shares with all other electromagnetic waves.

It is a transverse wave and can travel through a vacuum.

P5.2g Give examples of some practical uses of electromagnetic waves in the radio, microwave, infrared, visible, ultraviolet, X-ray and gamma ray regions

1.

Give two practical uses of radio waves.

Radio broadcasting; television broadcasting.

2.

Give two practical uses of microwaves.

Satellite communications; cooking food in microwave ovens.

3.

Give one practical use of infrared radiation and one use of visible light.

Infrared: remote controls. Visible light: photography.

4.

Give two practical uses of ultraviolet radiation.

Sterilising equipment; security marking.

5.

Give two practical uses of X-rays.

Medical imaging; airport security scanners.

6.

Give two practical uses of gamma rays.

Treating cancer; sterilising medical equipment.

P5.2h Describe how ultraviolet waves, X-rays and gamma rays can have hazardous effects, notably on human bodily tissues

1.

Why can ultraviolet radiation be hazardous to human tissue?

They can damage skin cells.

2.

State one harmful effect of excessive exposure to ultraviolet radiation.

Skin cancer.

3.

Why can X-rays damage living cells?

They are ionising radiation that can damage cells and DNA.

4.

Why can gamma rays damage living tissue?

They are highly penetrating ionising radiation that can damage living tissue.

5.

Explain why exposure to ionising electromagnetic radiation should be limited.

To reduce the risk of cell damage, mutations and cancer.

6.

Compare the potential hazards of ultraviolet, X-ray and gamma radiation to human bodily tissues.

Ultraviolet can damage skin, while X-rays and gamma rays are ionising radiations that can damage cells and increase the risk of cancer.

P5.2i Explain, in qualitative terms, how the differences in velocity, absorption and reflection between different types of waves in solids and liquids can be used both for detection and for exploration of structures which are hidden from direct observation, notably in our bodies

1.

How can differences in the absorption of waves by different tissues be used in medical imaging?

Different tissues absorb waves by different amounts, creating image contrast.

2.

Why are X-rays useful for producing images of bones?

Bone absorbs X-rays much more than soft tissue.

3.

How can reflected ultrasound waves be used to produce an image of structures inside the body?

Reflected ultrasound waves are detected to produce an image.

4.

Give one medical use of infrared radiation.

Thermal imaging.

5.

Give one medical use of gamma radiation in imaging.

Gamma camera imaging using radioactive tracers.

6.

Explain how differences in velocity, absorption and reflection allow waves to be used to investigate structures hidden inside the human body.

Differences in wave velocity, absorption and reflection allow structures inside the body to be detected and imaged without direct observation.

P5.2j Recall that radio waves can be produced by, or can themselves induce, oscillations in electrical circuits

1.

How can radio waves be produced by an electrical circuit?

By an oscillating electrical circuit.

2.

What type of electrical motion is needed to produce radio waves?

Oscillating charges (alternating current).

3.

What can happen when radio waves reach a suitable electrical circuit?

They can induce oscillations in the circuit.

4.

What type of electrical effect can radio waves induce in a receiving circuit?

An alternating current is induced.

5.

Explain how an oscillating electrical circuit can act as a source of radio waves.

Oscillating charges produce changing electric and magnetic fields that radiate as radio waves.

6.

Explain how radio waves can produce oscillations in a receiving electrical circuit.

Radio waves induce oscillations in a receiving circuit, allowing signals to be received.

P5.3a Recall that different substances may absorb, transmit, refract, or reflect electromagnetic waves in ways that vary with wavelength

1.

What is meant by absorption of an electromagnetic wave?

Absorption is when a material takes in the energy of an electromagnetic wave.

2.

What is meant by transmission of an electromagnetic wave?

Transmission is when an electromagnetic wave passes through a material.

3.

What is meant by reflection of an electromagnetic wave?

Reflection is when an electromagnetic wave bounces off a surface.

4.

What is meant by refraction of an electromagnetic wave?

Refraction is the change in direction of an electromagnetic wave as it enters a different substance because its speed changes.

5.

Explain why a substance may transmit some wavelengths of electromagnetic radiation but absorb others.

Different wavelengths interact differently with materials, so some wavelengths are transmitted while others are absorbed.

6.

Describe the different ways electromagnetic waves can interact with a substance.

Electromagnetic waves can be absorbed, transmitted, reflected or refracted depending on the material and the wavelength of the radiation.

P5.3b Explain how some effects are related to differences in the velocity of electromagnetic waves in different substances

1.

What happens to the velocity of an electromagnetic wave when it passes from one substance into another?

The velocity can increase or decrease.

2.

What is refraction?

Refraction is the change in direction of a wave when it enters a different medium because its speed changes.

3.

Why can a light ray change direction when it enters a different substance?

Because its velocity changes as it enters the new substance.

4.

What happens to the speed of light when it passes from air into glass?

The speed of light decreases.

5.

Explain why a light ray may bend when travelling from air into glass.

The light slows down and bends towards the normal.

6.

Explain how differences in wave velocity in different substances can cause refraction.

Differences in the velocity of electromagnetic waves in different substances cause refraction.

P5.3c Use ray diagrams to illustrate reflection, refraction and the similarities and differences between convex and concave lenses (qualitative only)

1.

Draw a ray diagram showing the reflection of a ray of light from a plane surface.

Reflected ray leaves the surface with the angle of reflection equal to the angle of incidence.

2.

Draw a ray diagram showing a ray of light refracting as it enters a glass block.

The ray bends towards the normal as it enters the glass block.

3.

Describe what happens to parallel rays of light passing through a convex lens.

Parallel rays converge to a focal point.

4.

Describe what happens to parallel rays of light passing through a concave lens.

Parallel rays diverge and spread out.

5.

Compare the effects of convex and concave lenses on parallel rays of light.

A convex lens converges parallel rays, whereas a concave lens diverges them.

6.

Explain how convex and concave lenses can be used to correct different vision problems.

Convex lenses are used to correct long-sightedness, while concave lenses are used to correct short-sightedness.

P5.3d Construct two-dimensional ray diagrams to illustrate reflection and refraction (qualitative only – equations not needed)

1.

Draw a ray diagram showing an incident ray, reflected ray and normal.

Draw an incident ray, a normal at 90° to the surface, and a reflected ray.

2.

Label the angle of incidence and angle of reflection on a ray diagram.

The angle of incidence is between the incident ray and the normal. The angle of reflection is between the reflected ray and the normal.

3.

Draw a ray diagram showing light passing from air into glass.

Draw the ray bending towards the normal as it enters the glass.

4.

Draw a ray diagram showing light passing from glass into air.

Draw the ray bending away from the normal as it leaves the glass.

5.

Describe how a ray bends when it enters a substance in which it travels more slowly.

It bends towards the normal.

6.

Construct a ray diagram showing both refraction as light enters a glass block and refraction as it leaves the block.

Draw the ray bending towards the normal as it enters the glass block and away from the normal as it leaves, emerging parallel to the original ray.

P5.3e Explain how colour is related to differential absorption, transmission and reflection

1.

Why does an object appear a particular colour?

Because it reflects certain wavelengths of visible light and absorbs the others.

2.

Why does a red object appear red when illuminated with white light?

It reflects red light and absorbs the other colours.

3.

What happens to the other wavelengths of visible light that are not reflected by a coloured object?

They are absorbed.

4.

Explain how a coloured filter produces coloured light.

It transmits only certain wavelengths while absorbing the rest.

5.

What is the difference between specular reflection and scattering?

Specular reflection is regular reflection from a smooth surface, whereas scattering is reflection in many directions from a rough surface.

6.

Explain how absorption, transmission and reflection determine the colour that we see.

The colour we see depends on which wavelengths are reflected or transmitted to our eyes and which wavelengths are absorbed.

P6.1a Recall that atomic nuclei are composed of both protons and neutrons, that the nucleus of each element has a characteristic positive charge

1.

Which two types of particle are found in an atomic nucleus?

Protons and neutrons.

2.

What charge does a proton have?

Positive charge.

3.

What charge does a neutron have?

No charge; it is neutral.

4.

Why does an atomic nucleus have an overall positive charge?

The nucleus contains positively charged protons and neutral neutrons, so it has an overall positive charge.

5.

What determines the characteristic positive charge of the nucleus of an element?

The number of protons in the nucleus.

6.

Compare the charges of protons and neutrons within an atomic nucleus.

Protons have a relative charge of +1, whereas neutrons have a relative charge of 0.

P6.1b Recall that atoms of the same elements can differ in nuclear mass by having different numbers of neutrons

1.

What is an isotope?

Atoms of the same element with the same number of protons but different numbers of neutrons.

2.

What is the same about the nuclei of isotopes of the same element?

They have the same number of protons.

3.

What is different about the nuclei of isotopes of the same element?

They have different numbers of neutrons.

4.

Why do isotopes of the same element have different nuclear masses?

They contain different numbers of neutrons, so their mass numbers are different.

5.

Two atoms have the same number of protons but different numbers of neutrons. What is their relationship?

They are isotopes of the same element.

6.

Explain why changing the number of neutrons does not change the identity of an element.

The identity of an element is determined by its number of protons, so changing only the number of neutrons does not change the element.

P6.1c Use the conventional representation for nuclei to relate the differences between isotopes

1.

What does the atomic number in nuclear notation represent?

The number of protons in the nucleus.

2.

What does the mass number in nuclear notation represent?

The total number of protons and neutrons in the nucleus.

3.

How can the number of neutrons in a nucleus be calculated from its nuclear notation?

Number of neutrons = mass number − atomic number.

4.

An atom has a mass number of 23 and an atomic number of 11. Calculate its number of neutrons.

Number of neutrons = 23 − 11 = 12.

5.

Compare the nuclear notation of two isotopes of the same element.

Isotopes have the same atomic number but different mass numbers.

6.

Use nuclear notation to explain how two isotopes can have the same identity and charge but different masses.

Isotopes have the same atomic number because they have the same number of protons, but different mass numbers because they have different numbers of neutrons.

P6.1d Recall that some nuclei are unstable and may emit alpha particles, beta particles, or neutrons, and electromagnetic radiation as gamma rays

1.

What is meant by an unstable nucleus?

A nucleus that may spontaneously decay and emit radiation.

2.

Name the four types of radiation or particles that may be emitted by an unstable nucleus.

Alpha particles, beta particles, neutrons and gamma rays.

3.

What type of electromagnetic radiation can be emitted by an unstable nucleus?

Gamma radiation.

4.

Which radioactive emission consists of a helium nucleus?

An alpha particle.

5.

Which radioactive emission is a high-speed electron?

A beta-minus particle.

6.

Describe what can happen when an unstable atomic nucleus undergoes radioactive decay.

It may emit radiation or particles and change into a more stable nucleus, often forming a different isotope or element.

P6.1e Relate the emission of alpha particles, beta particles, gamma radiation and neutrons to possible changes in the mass or the charge of the nucleus, or both

1.

How does alpha emission change the mass number of a nucleus?

The mass number decreases by 4.

2.

How does alpha emission change the atomic number of a nucleus?

The atomic number decreases by 2.

3.

How does beta-minus emission change the atomic number of a nucleus?

The atomic number increases by 1, while the mass number stays the same.

4.

How does gamma emission affect the mass number and atomic number of a nucleus?

Gamma emission causes no change to the mass number or atomic number.

5.

How does neutron emission affect the mass number and atomic number of a nucleus?

Neutron emission decreases the mass number by 1 but does not change the atomic number.

6.

Compare the changes in nuclear mass and charge caused by alpha, beta, gamma and neutron emissions.

Alpha emission changes both mass number and charge; beta-minus emission changes the charge but not the mass number; gamma emission changes neither; neutron emission changes the mass number but not the charge.

P6.1f Use names and symbols of common nuclei and particles to write balanced equations that represent radioactive decay

1.

State the nuclear symbol used to represent an alpha particle.

⁴₂He.

2.

State the nuclear symbol used to represent a beta particle.

⁰₋₁e.

3.

Complete a nuclear equation for the alpha decay of uranium-238.

²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He.

4.

Complete a nuclear equation for the beta decay of carbon-14.

¹⁴₆C → ¹⁴₇N + ⁰₋₁e.

5.

What must be conserved on both sides of a balanced radioactive decay equation?

Mass number and atomic number (charge) must be conserved.

6.

Write a balanced nuclear equation for a named radioactive isotope undergoing alpha or beta decay.

Example: ²²⁶₈₈Ra → ²²²₈₆Rn + ⁴₂He.

P6.1g Balance equations representing the emission of alpha, beta or gamma radiation in terms of the masses, and charges of the atoms involved

1.

What happens to the mass number when an alpha particle is emitted?

The mass number decreases by 4.

2.

What happens to the atomic number when an alpha particle is emitted?

The atomic number decreases by 2.

3.

What happens to the mass number and atomic number during beta-minus decay?

The mass number stays the same and the atomic number increases by 1.

4.

What happens to the mass number and atomic number during gamma emission?

Neither the mass number nor the atomic number changes.

5.

An unknown nucleus is produced by alpha decay. Explain how its mass number and atomic number can be determined.

Subtract 4 from the mass number and 2 from the atomic number of the original nucleus.

6.

Complete and balance nuclear equations involving alpha, beta and gamma emission using conservation of mass number and charge.

Balance nuclear equations by conserving both mass number and atomic number.

P6.1h Recall that in each atom its electrons are arranged at different distances from the nucleus, that such arrangements may change with absorption or emission of electromagnetic radiation and that atoms can become ions by loss of outer electrons

1.

How are electrons arranged around the nucleus of an atom?

In energy levels (electron shells) around the nucleus.

2.

What can happen to an inner electron when it absorbs energy from electromagnetic radiation?

It can move to a higher energy level.

3.

What happens when an excited electron loses energy and returns to a lower energy level?

It returns to a lower energy level.

4.

What is emitted when an electron loses energy and moves to a lower energy level?

Electromagnetic radiation (a photon).

5.

What is ionisation?

Ionisation is the gain or loss of electrons to form an ion.

6.

Explain how an atom can become an ion through the loss of an outer electron.

An atom becomes a positive ion by losing one or more outer electrons.

P6.1i Recall that changes in atoms and nuclei can also generate and absorb radiations over a wide frequency range

1.

What can changes within atoms and nuclei generate?

Electromagnetic radiation.

2.

What can atoms and nuclei do to electromagnetic radiation?

They can absorb electromagnetic radiation.

3.

From which part of the electromagnetic spectrum can radiation generated by changes in atoms and nuclei come?

From across the electromagnetic spectrum.

4.

Which high-frequency electromagnetic radiation can be produced by changes in atomic nuclei?

Gamma rays.

5.

Explain how changes in atoms can involve the absorption or emission of electromagnetic radiation.

Electrons absorb or emit electromagnetic radiation when changing energy levels.

6.

Describe the range of electromagnetic radiation that may be generated or absorbed by changes in atoms and nuclei.

Changes in atoms and nuclei can generate or absorb electromagnetic radiation over a wide range of frequencies.

P6.1j Explain the concept of half-life and how this is related to the random nature of radioactive decay

1.

What is meant by the half-life of a radioactive isotope?

The time taken for half the radioactive nuclei in a sample to decay.

2.

What happens to the number of undecayed radioactive nuclei after one half-life?

Half of the original undecayed nuclei remain.

3.

Why is radioactive decay described as a random process?

Because radioactive decay is random.

4.

Why is it impossible to predict exactly when an individual radioactive nucleus will decay?

Because it is impossible to predict when any individual nucleus will decay.

5.

Explain how dice can be used to model the random nature of radioactive decay and half-life.

Roll dice repeatedly and remove those showing a chosen number after each roll to model random decay and half-life.

6.

Explain how half-life can be used in radioactive dating.

Half-life can be used to determine the age of archaeological and geological samples by measuring the remaining radioactive isotope.

P6.1k Calculate the net decline, expressed as a ratio, during radioactive emission after a given (integral) number of half-lives

1.

What fraction of the original radioactive nuclei remains after one half-life?

1/2.

2.

What fraction of the original radioactive nuclei remains after three half-lives?

1/8.

3.

A sample initially contains 8000 radioactive nuclei. Calculate the number remaining after four half-lives.

500 radioactive nuclei.

4.

The activity of a radioactive source is initially 640 Bq. Calculate its activity after three half-lives.

80 Bq.

5.

A radioactive sample has a half-life of 5 days. Calculate the fraction of the original radioactive nuclei remaining after 20 days.

1/16.

6.

A source has an initial activity of 1600 Bq and a half-life of 10 years. Calculate its activity after 40 years.

100 Bq.

P6.1l Recall the differences in the penetration properties of alpha particles, beta particles and gamma rays

1.

Which type of nuclear radiation has the lowest penetrating power?

Alpha radiation.

2.

Which type of nuclear radiation has the greatest penetrating power?

Gamma radiation.

3.

What material can be used to stop alpha particles?

Paper, skin or a few centimetres of air.

4.

What material can be used to stop beta particles?

A thin sheet of aluminium.

5.

What materials can be used to reduce the penetration of gamma rays?

Thick lead or several metres of concrete.

6.

Compare the penetrating properties of alpha particles, beta particles and gamma rays.

Alpha is the least penetrating and is stopped by paper or skin; beta is moderately penetrating and is stopped by thin aluminium; gamma is the most penetrating and is reduced by thick lead or concrete.

P6.2a Recall the differences between contamination and irradiation effects and compare the hazards associated with these two

1.

What is meant by radioactive contamination?

Radioactive contamination is the unwanted presence of radioactive material on or inside an object or person.

2.

What is meant by irradiation?

Irradiation is exposure to radiation from a radioactive source.

3.

State the difference between contamination and irradiation.

Contamination involves radioactive material being transferred onto or into an object; irradiation does not involve transfer of radioactive material.

4.

Why can contamination continue to expose a person to radiation after the original source has been removed?

The contaminating material remains present and continues to emit radiation until it is removed or decays.

5.

Why does irradiation not necessarily make an object radioactive?

Irradiation does not make an object radioactive because no radioactive material is transferred to it.

6.

Compare the hazards associated with contamination and irradiation.

Contamination can cause prolonged internal or external exposure, whereas irradiation only occurs while the source is present, although both can damage living cells.

P6.2b Explain why the hazards associated with radioactive material differ according to the half-life involved

1.

What does a short half-life indicate about the rate at which a radioactive material decays?

It decays rapidly.

2.

Why can a radioactive source with a short half-life have a high activity?

Many nuclei decay each second, producing a high activity.

3.

Why can a radioactive material with a long half-life remain hazardous for a long time?

It decays slowly and can remain radioactive for a long time.

4.

Explain why half-life must be considered when choosing a radioactive isotope for a particular use.

The half-life must be long enough for the isotope to perform its function but not so long that it remains hazardous unnecessarily.

5.

Explain why an isotope used in a smoke detector needs a suitable half-life.

It needs a sufficiently long half-life to remain effective for many years without frequent replacement.

6.

Compare the hazards presented by radioactive materials with short and long half-lives.

Short-half-life materials can have high activity but become safe more quickly; long-half-life materials usually have lower activity but remain hazardous for much longer.

P6.2c Describe the different uses of nuclear radiations for exploration of internal organs, and for control or destruction of unwanted tissue

1.

What is a radioactive tracer?

A radioactive substance introduced into the body so its movement or concentration can be monitored.

2.

How can a radioactive tracer be used to explore the function of an internal organ?

It is taken into the body and its radiation is detected to show how the organ is working.

3.

How can radiation emitted by a tracer be detected from outside the body?

Using an external detector such as a gamma camera.

4.

What is radiotherapy?

The use of ionising radiation to treat disease, particularly cancer.

5.

Explain how nuclear radiation can be used to destroy unwanted tissue.

A controlled dose of radiation is directed at the unwanted tissue to damage or destroy its cells.

6.

Compare the use of nuclear radiation for exploring internal organs with its use for controlling or destroying unwanted tissue.

Tracers use small amounts of radiation for diagnosis and monitoring, while radiotherapy uses larger targeted doses to destroy unwanted tissue.

P6.2d Recall that some nuclei are unstable and may split, and relate such effects to radiation which might emerge, to transfer of energy to other particles and to the possibility of chain reactions

1.

What is nuclear fission?

The splitting of a large unstable nucleus into two smaller nuclei.

2.

What must an unstable nucleus usually absorb before nuclear fission occurs?

A neutron.

3.

What happens to an unstable nucleus during nuclear fission?

It splits into two smaller daughter nuclei.

4.

What particles and radiation may be released during nuclear fission?

Neutrons, gamma radiation and energy.

5.

Explain how neutrons released during fission can cause a chain reaction.

The released neutrons can be absorbed by other unstable nuclei, causing further fission reactions.

6.

Describe how nuclear fission results in energy transfer and the possibility of a chain reaction.

Fission transfers energy to the daughter nuclei, neutrons and radiation; the released neutrons can trigger further fissions, producing a chain reaction.

P6.2e Describe the process of nuclear fusion

1.

What is nuclear fusion?

The joining of two small atomic nuclei to form a larger nucleus.

2.

What happens to small atomic nuclei during nuclear fusion?

They combine.

3.

What type of nucleus is formed during nuclear fusion?

A larger, heavier nucleus.

4.

What happens to mass during a nuclear fusion reaction?

Some mass is lost.

5.

How is energy released during nuclear fusion?

The lost mass is converted into energy.

6.

Describe the process of nuclear fusion and explain how mass may be converted into the energy of radiation.

In fusion, small nuclei join to form a larger nucleus; a small decrease in mass is converted into energy, which is released mainly as radiation and kinetic energy.

P7.1a Describe for situations where there are energy transfers in a system, that there is no net change to the total energy of a closed system (qualitative only)

1.

State the law of conservation of energy.

Energy cannot be created or destroyed; it can only be transferred between stores or pathways.

2.

What is meant by a closed system?

A closed system is one in which no energy enters or leaves the system.

3.

What happens to the total energy of a closed system when energy transfers occur?

The total energy remains constant.

4.

Can energy be created or destroyed in a closed system?

No. Energy cannot be created or destroyed in a closed system.

5.

Explain why the total energy remains constant even when energy is transferred between different stores.

Energy is simply transferred between different energy stores, so the total amount of energy stays the same.

6.

Describe the energy changes in a closed system and explain why there is no net change in total energy.

Energy may be transferred between kinetic, gravitational, thermal, chemical or other stores, but the total energy of the closed system remains constant.

P7.1b Describe all the changes involved in the way energy is stored when a system changes for common situations

1.

Describe the energy store changes when an object is projected upwards.

Kinetic → Gravitational potential → Thermal (and sound) as it falls back down.

2.

Describe the energy store changes when a moving object hits an obstacle.

Kinetic → Thermal (and sound) energy stores.

3.

Describe the energy store changes when an object is accelerated by a constant force.

Chemical → Kinetic energy stores (or electrical → kinetic for an electric motor).

4.

Describe the energy store changes when a vehicle slows down.

Kinetic → Thermal energy stores of the brakes, tyres, road and surroundings.

5.

Describe the energy store changes when water is brought to the boil in an electric kettle.

Chemical/Electrical → Thermal energy store of the water.

6.

Describe the energy store changes when an object moves up a slope and then comes to rest.

Kinetic → Gravitational potential while moving uphill, then gravitational potential → Thermal as it comes to rest due to friction.

P7.1c Describe the changes in energy involved when a system is changed by heating (in terms of temperature change and specific heat capacity), by work done by forces, and by work done when a current flows

1.

What happens to the thermal energy store of an object when it is heated?

The thermal energy store increases.

2.

How does the specific heat capacity of a substance affect the energy needed to increase its temperature?

A higher specific heat capacity means more energy is needed to raise the temperature by the same amount.

3.

Describe an energy transfer that occurs when a force does work on an object.

Work done transfers energy, for example from a chemical store to a kinetic store when pushing an object.

4.

Describe the energy changes when a current flows through a heating element.

Electrical energy is transferred to the thermal energy store of the heating element and surroundings.

5.

Explain how work done by a force can change the energy stored in a system.

Work done transfers energy between stores, such as increasing an object's kinetic or gravitational potential energy.

6.

Compare energy transfers caused by heating, forces doing work and an electric current doing work.

Heating transfers energy to thermal stores, forces transfer energy to kinetic, gravitational or elastic stores, and electric currents transfer energy from electrical stores to other energy stores.

P7.1d Make calculations of the energy changes associated with changes in a system, recalling or selecting the relevant equations for mechanical, electrical, and thermal processes; thereby express in quantitative form and on a common scale the overall redistribution of energy in the system

1.

State the equation linking work done, force and distance moved in the direction of the force.

Work done = Force × Distance (W = Fd).

2.

State the equation linking energy transferred, charge and potential difference.

Energy transferred = Charge × Potential difference (E = QV).

3.

State the equation linking change in thermal energy, mass, specific heat capacity and temperature change.

Change in thermal energy = Mass × Specific heat capacity × Temperature change (ΔE = mcΔθ).

4.

Calculate the work done when a force of 50 N moves an object 4 m in the direction of the force.

Work done = 50 × 4 = 200 J.

5.

An appliance transfers 3.6 MJ of energy. Express this energy in kWh.

3.6 MJ = 1 kWh.

6.

A television transfers 7.2 MJ of energy. Express this energy in kWh.

2.0 kWh.

P7.1e Calculate the amounts of energy associated with a moving body, a stretched spring and an object raised above ground level

1.

State the equation used to calculate the kinetic energy of a moving object.

Kinetic energy = ½mv².

2.

State the equation used to calculate the elastic potential energy stored in a stretched spring.

Elastic potential energy = ½ke².

3.

State the equation used to calculate the gravitational potential energy gained by an object raised above the ground.

Gravitational potential energy = mgh.

4.

Calculate the kinetic energy of a 5 kg object travelling at 4 m/s.

KE = ½ × 5 × 4² = 40 J.

5.

Calculate the elastic potential energy stored in a spring with a spring constant of 200 N/m stretched by 0.10 m.

EPE = ½ × 200 × 0.10² = 1 J.

6.

Calculate the gravitational potential energy gained by a 10 kg object raised through a height of 5 m.

GPE = 10 × 9.8 × 5 = 490 J (accept 500 J if using g = 10 N/kg).

P7.2a Describe, with examples, the process by which energy is dissipated, so that it is stored in less useful ways

1.

What is meant by energy being dissipated?

Energy being dissipated means it is transferred to the thermal energy stores of the surroundings, where it becomes less useful.

2.

Does dissipated energy disappear from a system?

No. Dissipated energy is not destroyed; it is transferred to less useful energy stores.

3.

Give an example of energy being dissipated due to friction.

Friction between car brakes and wheels transfers kinetic energy to the thermal energy stores of the brakes and surroundings.

4.

What usually happens to the thermal energy store of the surroundings when energy is dissipated?

The thermal energy store of the surroundings increases.

5.

Explain why dissipated energy is described as being stored in less useful ways.

The energy is spread out in the surroundings, making it more difficult to use for useful work.

6.

Describe the energy dissipation that occurs when a moving vehicle slows down.

As a moving vehicle slows down, its kinetic energy is transferred mainly to the thermal energy stores of the brakes, tyres, road and surrounding air (with some sound).

P7.2b Describe how, in different domestic devices, energy is transferred from batteries or the a.c. from the mains

1.

What energy store provides energy in a battery-powered device?

The chemical energy store of the battery.

2.

How is energy transferred to a domestic appliance connected to the mains?

Energy is transferred electrically by an alternating current (a.c.) from the mains supply.

3.

Describe the useful energy transfer in an electric kettle.

Electrical → Thermal energy stores of the heating element and water.

4.

Describe the useful energy transfer in an electric motor.

Electrical → Kinetic energy stores.

5.

Give an example of how energy can be wasted within a motor.

Some energy is transferred to the thermal energy store of the motor and surroundings (and sometimes sound).

6.

Explain how energy supplied electrically to a domestic device can be transferred into both useful and wasted energy stores.

Electrical energy is transferred into useful energy stores (such as kinetic, light or thermal) while some is dissipated to the surroundings as thermal energy and sound.

P7.2c Describe, with examples, the relationship between the power ratings for domestic electrical appliances and how this is linked to the changes in stored energy when they are in use

1.

What is meant by the power rating of an electrical appliance?

The power rating is the rate at which an appliance transfers energy.

2.

What is the unit of power?

Watt (W).

3.

What does it mean if an appliance has a power rating of 2000 W?

It transfers 2000 joules of energy every second.

4.

Which transfers more energy each second: a 500 W appliance or a 1500 W appliance?

The 1500 W appliance.

5.

Explain why a high-power kettle can transfer energy to water more quickly than a low-power kettle.

It transfers more energy each second, so the water heats up faster.

6.

Describe the relationship between the power rating of an appliance and the rate at which energy stores change.

The greater the power rating, the faster energy is transferred and the more quickly energy stores change.

P7.2d Calculate energy efficiency for any energy transfer

1.

State the equation used to calculate energy efficiency.

Efficiency = Useful energy output ÷ Total energy input (×100% for percentage).

2.

A device receives 500 J of energy and transfers 400 J usefully. Calculate its efficiency.

Efficiency = 400 ÷ 500 = 0.80 (80%).

3.

A motor receives 2000 J of energy and transfers 1500 J usefully. Calculate its efficiency as a percentage.

Efficiency = (1500 ÷ 2000) × 100 = 75%.

4.

A machine is 80% efficient and receives 1000 J of energy. Calculate the useful energy transferred.

Useful energy = 0.80 × 1000 = 800 J.

5.

A device transfers 600 J usefully and is 75% efficient. Calculate the total input energy.

Total input = 600 ÷ 0.75 = 800 J.

6.

Calculate the wasted energy when a device receives 2500 J and has an efficiency of 60%.

Useful energy = 0.60 × 2500 = 1500 J. Wasted energy = 2500 − 1500 = 1000 J.

P7.2e Describe ways to increase efficiency

1.

What is meant by increasing the efficiency of a device?

Increasing efficiency means a greater proportion of the input energy is transferred usefully.

2.

How can reducing friction increase the efficiency of a machine?

Lubrication reduces friction, so less energy is dissipated as thermal energy.

3.

How can thermal insulation increase the efficiency of a heating system?

Thermal insulation reduces energy transfer by heating, so more energy remains useful.

4.

Why can reducing unwanted sound increase the efficiency of some devices?

Less energy is dissipated as sound, leaving more available for useful transfers.

5.

Give two ways in which the efficiency of a machine could be increased.

Examples: lubricate moving parts and add thermal insulation (accept streamlined designs or low-friction bearings where appropriate).

6.

Explain why reducing unwanted energy transfers increases efficiency.

Reducing unwanted energy transfers means less energy is wasted, so a greater proportion becomes useful output.

P7.2f Explain ways of reducing unwanted energy transfer

1.

How does lubrication reduce unwanted energy transfer in moving machinery?

Lubrication reduces friction, so less energy is transferred to unwanted thermal energy stores.

2.

How does thermal insulation reduce unwanted energy transfer?

Thermal insulation slows the transfer of energy by heating to the surroundings.

3.

Why can cavity wall insulation reduce energy transfer from a house?

Cavity wall insulation traps air, reducing energy transfer through the walls.

4.

How can loft insulation reduce unwanted energy transfer from a building?

Loft insulation reduces energy transfer through the roof, keeping more thermal energy inside the building.

5.

Explain how reducing friction can reduce energy dissipation.

Reducing friction means less kinetic energy is dissipated as thermal energy.

6.

Explain two ways unwanted energy transfer from a building can be reduced.

Unwanted energy transfer from a building can be reduced by cavity wall insulation and loft insulation (accept double glazing, floor insulation or draught proofing).

P7.2g Describe how the rate of cooling of a building is affected by the thickness and thermal conductivity of its walls (qualitative only)

1.

What is meant by thermal conductivity?

Thermal conductivity is a measure of how easily energy is transferred through a material by heating.

2.

How does increasing the thickness of a wall affect the rate of cooling of a building?

Increasing the wall thickness reduces the rate of cooling.

3.

How does decreasing the thermal conductivity of a wall affect the rate of cooling?

Lower thermal conductivity reduces the rate of energy transfer, so the building cools more slowly.

4.

Which is a better thermal insulator: a material with high or low thermal conductivity?

A material with low thermal conductivity is the better thermal insulator.

5.

Explain why thick walls made from materials with low thermal conductivity reduce energy transfer.

Thick walls made from materials with low thermal conductivity reduce the transfer of thermal energy to the surroundings.

6.

Compare the rate of cooling of two identical buildings when one has thicker, better-insulated walls.

The building with thicker, better-insulated walls cools more slowly because less thermal energy is transferred through the walls.

P8.1a Recall typical speeds encountered in everyday experience for wind and sound, and for walking, running, cycling and other transportation systems

1.

What is a typical walking speed for a person?

A typical walking speed is 1.5 m/s.

2.

What is a typical running speed for a person?

A typical running speed is 3 m/s.

3.

What is a typical cycling speed?

A typical cycling speed is 6 m/s.

4.

What is the approximate speed of sound in air?

The approximate speed of sound in air is 340 m/s.

5.

Give a typical speed for a car travelling on a road.

A typical speed for a car travelling on a road is 30 m/s (about 70 mph).

6.

Compare typical speeds for walking, running, cycling, road transport, wind and sound.

Walking is slowest, followed by running, cycling, road transport, wind (typically around 10–20 m/s), while sound travels much faster at about 340 m/s.

P8.1b Estimate the magnitudes of everyday accelerations

1.

What is meant by acceleration?

Acceleration is the rate of change of velocity.

2.

State the unit used to measure acceleration.

The unit of acceleration is m/s².

3.

Estimate a reasonable acceleration for a car pulling away from traffic lights.

A reasonable acceleration for a car pulling away from traffic lights is about 2 m/s².

4.

Estimate a reasonable deceleration for a bicycle coming to a stop.

A reasonable deceleration for a bicycle coming to a stop is about 2–3 m/s².

5.

Which would usually have the greater acceleration: a person beginning to walk or a car accelerating rapidly?

A rapidly accelerating car would usually have the greater acceleration.

6.

Estimate the magnitude of the acceleration in a given everyday situation and explain whether your estimate is reasonable.

Everyday accelerations are usually between 1 and 5 m/s², depending on the vehicle and situation.

P8.1c Make calculations using ratios and proportional reasoning to convert units and to compute rates

1.

Convert 72 km/h into m/s.

72 km/h = 20 m/s.

2.

Convert 15 m/s into km/h.

15 m/s = 54 km/h.

3.

A car travels 150 km in 2.5 hours. Calculate its average speed in km/h.

Average speed = 150 ÷ 2.5 = 60 km/h.

4.

A cyclist travels 6000 m in 20 minutes. Calculate the average speed in m/s.

Time = 20 min = 1200 s. Speed = 6000 ÷ 1200 = 5 m/s.

5.

A vehicle travels at 25 m/s for 40 s. Calculate the distance travelled.

Distance = 25 × 40 = 1000 m.

6.

A car increases its speed from 10 m/s to 30 m/s in 5 s. Calculate its acceleration.

Acceleration = (30 − 10) ÷ 5 = 4 m/s².

P8.1d Explain methods of measuring human reaction times and recall typical results

1.

What is meant by reaction time?

Reaction time is the time taken to respond to a stimulus.

2.

Describe how a ruler-drop experiment can be used to measure human reaction time.

A ruler is dropped without warning and the distance fallen before it is caught is measured.

3.

What is a typical human reaction time?

A typical human reaction time is about 0.2–0.3 seconds.

4.

Why should a reaction-time experiment be repeated several times?

Repeating the experiment improves the reliability of the results.

5.

How can the reliability of a reaction-time investigation be improved?

Reliability can be improved by repeating the test, calculating a mean and ignoring anomalous results.

6.

Explain how the distance a ruler falls can be used to determine a person's reaction time.

A greater distance fallen means a longer reaction time, because the ruler has been falling for longer before being caught.

P8.1e Explain the factors which affect the distance required for road transport vehicles to come to rest in emergencies and the implications for safety

1.

What is thinking distance?

Thinking distance is the distance travelled during the driver's reaction time.

2.

What is braking distance?

Braking distance is the distance travelled after the brakes are applied until the vehicle stops.

3.

State the relationship between thinking distance, braking distance and overall stopping distance.

Stopping distance = Thinking distance + Braking distance.

4.

Give three factors that can increase thinking distance.

Thinking distance is increased by tiredness, alcohol/drugs and distractions (e.g. using a phone).

5.

Give three factors that can increase braking distance.

Braking distance is increased by wet/icy roads, worn tyres and poor brakes.

6.

Explain how speed, tiredness, alcohol, road conditions and tyre condition can affect stopping distance and road safety.

Higher speed increases both thinking and braking distance, while tiredness, alcohol, poor road conditions and worn tyres all increase stopping distance, making collisions more likely.

P8.1f Estimate how the distances required for road vehicles to stop in an emergency varies over a range of typical speeds

1.

What happens to thinking distance as the speed of a vehicle increases?

Thinking distance increases directly with speed.

2.

What happens to braking distance as the speed of a vehicle increases?

Braking distance increases much more rapidly as speed increases.

3.

Why does doubling the speed of a vehicle more than double its overall stopping distance?

Doubling the speed more than doubles the stopping distance because braking distance increases approximately with the square of the speed.

4.

Estimate whether a car travelling at 60 mph would require a greater or smaller stopping distance than one travelling at 30 mph.

A car travelling at 60 mph requires a much greater stopping distance than one travelling at 30 mph.

5.

Explain why braking distance increases rapidly as vehicle speed increases.

Braking distance increases rapidly because the vehicle has much more kinetic energy that must be removed.

6.

Use stopping-distance data for a range of speeds to estimate the stopping distance at a given speed.

Stopping-distance data show that higher speeds require much longer stopping distances, especially above typical town-driving speeds.

P8.1g Explain the dangers caused by large decelerations

1.

What is meant by deceleration?

Deceleration is negative acceleration (slowing down).

2.

Why can a large deceleration be dangerous to passengers in a vehicle?

Large decelerations produce large forces on passengers.

3.

How do seat belts reduce the dangers caused by large decelerations?

Seat belts increase the time taken to stop, reducing the force on the body.

4.

How do airbags reduce the forces acting on passengers during a collision?

Airbags increase the stopping time and spread the force over a larger area.

5.

How do crumple zones reduce the forces experienced during a collision?

Crumple zones absorb energy and increase the time over which the vehicle stops.

6.

Explain why increasing the time taken for a vehicle or passenger to stop can reduce the force experienced.

Increasing the stopping time reduces the force because the same change in momentum occurs over a longer time.

P8.1h Estimate the forces involved in typical situations on a public road

1.

State the equation linking resultant force, mass and acceleration.

Force = mass × acceleration (F = ma).

2.

Calculate the force required to accelerate a 1000 kg car at 2 m/s².

Force = 1000 × 2 = 2000 N.

3.

Calculate the force acting on a 1500 kg vehicle decelerating at 4 m/s².

Force = 1500 × 4 = 6000 N (opposite to the direction of motion).

4.

Estimate a reasonable force needed to accelerate a typical car on a public road.

A typical force accelerating a family car is around 2000–5000 N.

5.

Explain why a heavier vehicle requires a larger force to produce the same acceleration as a lighter vehicle.

A heavier vehicle needs a greater force to produce the same acceleration because it has a larger mass.

6.

Estimate the force acting on a vehicle in a given road situation using its approximate mass and acceleration.

Estimate the force by multiplying the vehicle's approximate mass by its acceleration.

P8.1i Estimate, for everyday road transport, the speed, accelerations and forces involved in large accelerations

1.

Give a reasonable estimate for the speed of a car travelling on a fast road.

A reasonable speed for a fast-moving car is about 30 m/s (≈70 mph).

2.

Give a reasonable estimate for the acceleration of a car accelerating rapidly.

A rapidly accelerating car may have an acceleration of about 5 m/s².

3.

State the equation used to calculate force from mass and acceleration.

F = ma.

4.

A 1200 kg car accelerates at 5 m/s². Calculate the resultant force.

Force = 1200 × 5 = 6000 N.

5.

Explain why large accelerations can result in large forces.

Large accelerations produce large resultant forces because force is proportional to acceleration.

6.

Estimate the speed, acceleration and force involved when a typical road vehicle undergoes a large acceleration.

A typical car may travel at around 30 m/s, accelerate at 5 m/s², and experience a force of around 6000 N during rapid acceleration.

P8.2a Describe the main energy sources available for use on Earth, compare the ways in which they are used and distinguish between renewable and non-renewable sources

1.

What is meant by a renewable energy source?

A renewable energy resource is one that is naturally replenished, so it will not run out on a human timescale.

2.

What is meant by a non-renewable energy source?

A non-renewable energy resource is one that is finite and will eventually run out because it is used faster than it is replaced.

3.

Classify fossil fuels, nuclear fuel, biofuel, wind, hydroelectricity, tides and the Sun as renewable or non-renewable energy sources.

Renewable resources: wind, solar, hydroelectric, tidal, wave, geothermal and biofuel. Non-renewable resources: coal, oil, natural gas and nuclear fuel.

4.

Describe how fossil fuels are used to generate electricity.

Fossil fuels are burned to heat water, producing steam that turns a turbine connected to a generator. Nuclear power stations use nuclear fission to heat water and produce steam.

5.

Describe how wind, hydroelectricity and tidal energy can be used to generate electricity.

Wind, hydroelectric and tidal power use moving air or water to turn turbines. Solar cells convert light energy directly into electrical energy.

6.

Compare renewable and non-renewable energy sources in terms of their availability, reliability and environmental impact.

Renewable resources are sustainable and usually produce less carbon dioxide, but many depend on weather conditions. Non-renewable resources provide reliable electricity generation but are finite and can cause pollution or produce radioactive waste.

P8.2b Explain patterns and trends in the use of energy resources

1.

What is meant by a trend in the use of an energy resource?

The use of renewable energy resources has generally increased, while the use of fossil fuels such as coal has decreased.

2.

How has the use of different energy resources changed over time?

Renewable energy use has increased because it reduces carbon dioxide emissions and renewable resources will not run out.

3.

Give two reasons why the use of fossil fuels may decrease over time.

Coal use has decreased because it produces large amounts of carbon dioxide and other pollutants.

4.

Give two reasons why the use of renewable energy resources may increase over time.

Different countries use different energy resources depending on their geography, climate, natural resources and energy demand.

5.

Explain how environmental concerns can affect the choice of energy resources.

Improvements in technology have made renewable energy sources more efficient and cheaper to use.

6.

Interpret data showing the changing use of different energy resources over time and describe the main trends.

When interpreting data on energy resources, describe the trend, compare different resources and support your answer with figures from the data.

P8.2c Recall that, in the national grid, electrical power is transferred at high voltages from power stations, and then transferred at lower voltages in each locality for domestic use

1.

What is the National Grid?

The National Grid is a network of cables and transformers that transfers electrical power from power stations to homes and businesses.

2.

At what type of potential difference is electrical power transferred over long distances in the National Grid?

Electricity is transferred through the National Grid at a high potential difference (high voltage).

3.

Why is electrical power transferred at high potential differences over long distances?

High voltages reduce the current needed to transfer the same amount of power.

4.

What happens to the potential difference before electricity enters homes?

Before electricity reaches homes, transformers reduce the potential difference to about 230 V.

5.

Where is electrical power generated before being transferred through the National Grid?

Electricity is generated in power stations before entering the National Grid.

6.

Describe how electrical power is transferred from a power station to a domestic property using the National Grid.

Electrical power is generated, stepped up to a high potential difference, transferred through transmission cables and then stepped down to about 230 V before entering homes.

P8.2d Recall that step-up and step-down transformers are used to change the potential difference as power is transferred from power stations

1.

What is the purpose of a step-up transformer?

A step-up transformer increases the potential difference.

2.

What is the purpose of a step-down transformer?

A step-down transformer decreases the potential difference.

3.

Where are step-up transformers used in the National Grid?

Step-up transformers are used immediately after electricity is generated at power stations.

4.

Where are step-down transformers used in the National Grid?

Step-down transformers are used near towns, villages and homes before electricity is supplied to consumers.

5.

Why must the potential difference be reduced before electricity is supplied to homes?

High transmission voltages would be dangerous for homes, so the potential difference must be reduced before domestic use.

6.

Describe how step-up and step-down transformers are used as electrical power is transferred from power stations to consumers.

Electricity is stepped up for efficient transmission and stepped down again to provide a safe domestic supply.

P8.2e Explain how the national grid is an efficient way to transfer energy

1.

Why is some energy wasted when electrical power is transferred through cables?

Electrical energy is dissipated as heat because transmission cables have resistance.

2.

In what form is energy usually dissipated from transmission cables?

The wasted energy is transferred to the thermal energy stores of the cables and surroundings.

3.

How does increasing the potential difference affect the current for the same power transfer?

Increasing the potential difference decreases the current needed to transfer the same power.

4.

Why does reducing the current reduce energy losses from transmission cables?

A lower current produces less heating in the transmission cables.

5.

Why are high potential differences used to transfer electrical power over long distances?

Less heating means less energy is wasted during transmission.

6.

Explain how the National Grid reduces unwanted energy transfers and transfers energy efficiently.

The National Grid transfers electricity efficiently because it uses very high potential differences, reducing the current and therefore reducing energy losses in the transmission cables.

P8.2f Link the potential differences and numbers of turns of a transformer to the power transfer involved; relate this to the advantages of power transmission at high voltages

1.

State the relationship between the potential differences and numbers of turns in the primary and secondary coils of a transformer.

Primary potential difference ÷ Secondary potential difference = Primary number of turns ÷ Secondary number of turns.

2.

What happens to the potential difference when a transformer has more turns on the secondary coil than on the primary coil?

If the secondary coil has more turns than the primary coil, the transformer is a step-up transformer.

3.

State the equation linking primary potential difference and current to secondary potential difference and current for a transformer.

Primary power = Secondary power (for an ideal transformer).

4.

A transformer has a primary potential difference of 230 V and a primary current of 4 A. The secondary potential difference is 920 V. Calculate the secondary current.

Primary power = 230 × 4 = 920 W. Secondary current = 920 ÷ 920 = 1 A.

5.

Explain why increasing the transmission potential difference reduces the current for the same power transfer.

As the potential difference increases, the current decreases for the same power transfer.

6.

Explain why transmitting electrical power at high potential differences reduces energy losses in the National Grid.

Using a high potential difference reduces the current, so less energy is dissipated as heat in the transmission cables, making the National Grid more efficient.

P8.2g Recall that the domestic supply in the UK is a.c. at 50 Hz and about 230 volts

1.

Is the UK domestic electricity supply a.c. or d.c.?

The UK mains electricity supply is alternating current (a.c.).

2.

What is the frequency of the UK domestic electricity supply?

The frequency is 50 Hz.

3.

What is the potential difference of the UK domestic electricity supply?

The potential difference is approximately 230 V.

4.

What does a frequency of 50 Hz mean?

A frequency of 50 Hz means the current changes direction 50 times every second.

5.

State the two key numerical values used to describe the UK domestic electricity supply.

The domestic electricity supply has a potential difference of about 230 V and a frequency of 50 Hz.

6.

Describe the domestic electricity supply used in the UK.

UK mains electricity is an alternating current supply with a potential difference of about 230 V and a frequency of 50 Hz.

P8.2h Explain the difference between direct and alternating voltage

1.

What is meant by direct voltage?

A direct voltage (d.c.) has a constant polarity and drives current in one direction only.

2.

What is meant by alternating voltage?

An alternating voltage (a.c.) continually changes its polarity and size.

3.

How does the polarity of a direct voltage change with time?

Batteries provide direct voltage.

4.

How does the polarity of an alternating voltage change with time?

The UK mains supply provides alternating voltage.

5.

Compare the voltage-time traces for a.c. and d.c. supplies.

A d.c. voltage stays constant with time, whereas an a.c. voltage repeatedly changes from positive to negative.

6.

Explain the difference between the potential difference supplied by a battery and that supplied by the UK mains.

Direct voltage causes current to flow in one direction only, while alternating voltage causes current to repeatedly reverse direction.

P8.2i Recall the differences in function between the live, neutral and earth mains wires, and the potential differences between these wires

1.

What is the function of the live wire in a mains circuit?

The live wire carries the alternating potential difference from the supply to the appliance.

2.

What is the function of the neutral wire in a mains circuit?

The neutral wire completes the circuit and is close to 0 V.

3.

What is the function of the earth wire in a mains circuit?

The earth wire is a safety wire connected to the metal case of an appliance.

4.

What is the potential difference between the live and neutral wires in the UK mains supply?

The potential difference between the live wire and the neutral wire is about 230 V.

5.

What is the approximate potential difference between the neutral wire and earth?

The potential difference between the neutral wire and Earth is approximately 0 V.

6.

Compare the functions and potential differences of the live, neutral and earth wires in a mains circuit.

The live wire carries the dangerous supply, the neutral wire returns the current, and the earth wire provides a safe path for current if a fault develops.

P8.2j Explain that a live wire may be dangerous even when a switch in a mains circuit is open, and explain the dangers of providing any connection between the live wire and earth

1.

Why can the live wire still be dangerous when a switch is open?

The live wire remains at about 230 V relative to Earth even when a switch is open.

2.

Why should a switch be connected in the live wire rather than the neutral wire?

The switch should always be connected in the live wire so that opening it disconnects the appliance from the live supply.

3.

What could happen if a person provides a connection between the live wire and earth?

Touching the live wire while connected to Earth can allow a large current to pass through the body, causing a potentially fatal electric shock.

4.

Why can touching a live wire result in an electric shock?

Connecting the live wire directly to Earth creates a very large current.

5.

How does insulation help protect a user from the live parts of an electrical device?

The earth wire provides a low-resistance pathway that allows the fuse to melt or the circuit breaker to disconnect the supply if a fault occurs.

6.

Explain why contact between the live wire and an earthed metal case can be dangerous and how insulation reduces this risk.

Good insulation prevents contact with the live wire, while the earth wire and fuse or circuit breaker protect users by disconnecting the electricity supply if a fault causes the live wire to contact the metal case of an appliance.

P8.3a Explain the red-shift of light as seen from galaxies which are receding (qualitative only). The change with distance of each galaxy's speed is evidence of an expanding universe

1.

What is meant by red-shift?

Red-shift is the increase in the wavelength of light from an object moving away from the observer.

2.

What happens to the wavelength of light from a galaxy that is moving away from Earth?

The wavelength of light from a galaxy moving away from Earth increases.

3.

What happens to the frequency of light when it is red-shifted?

As light is red-shifted, its frequency decreases.

4.

What does red-shift tell us about the motion of distant galaxies?

Red-shift shows that distant galaxies are moving away from the Earth.

5.

What relationship is observed between the distance of a galaxy and the speed at which it is receding?

The further away a galaxy is, the faster it is receding from the Earth.

6.

Explain how observations of red-shift provide evidence that the universe is expanding.

Since almost all distant galaxies show red-shift, it provides evidence that the Universe is expanding.

P8.3b Explain how red shift and other evidence can be linked to the Big-Bang model

1.

What is the Big Bang model?

The Big Bang model states that the Universe began from an extremely hot, dense state about 13.8 billion years ago and has been expanding ever since.

2.

How does red-shift provide evidence for the Big Bang model?

Red-shift provides evidence because it shows that most galaxies are moving away from each other, meaning the Universe is expanding.

3.

What is cosmic microwave background radiation?

Cosmic microwave background (CMB) radiation is low-energy microwave radiation found throughout the Universe.

4.

Why is cosmic microwave background radiation evidence for the Big Bang model?

The CMB is evidence for the Big Bang because it is thought to be the remaining thermal radiation from the early Universe.

5.

Explain how an expanding universe supports the idea that the universe was once much smaller and denser.

If the Universe is expanding now, then in the past it must have been much smaller, hotter and denser.

6.

Explain how red-shift and cosmic microwave background radiation together provide evidence for the Big Bang model.

Together, red-shift and the cosmic microwave background radiation provide strong evidence supporting the Big Bang model.

P8.3c Recall that our Sun was formed from dust and gas drawn together by gravity and explain how this caused fusion reactions, leading to equilibrium between gravitational collapse and expansion due to the energy released during fusion

1.

What material was the Sun originally formed from?

The Sun was originally formed from a cloud of dust and gas called a nebula.

2.

What force caused dust and gas to be drawn together during the formation of the Sun?

Gravity caused the dust and gas to be drawn together.

3.

Why did the temperature increase as the material forming the Sun collapsed together?

As the material collapsed, gravitational potential energy was converted into thermal energy, increasing the temperature and pressure.

4.

What nuclear process began when the temperature became sufficiently high?

When the temperature became sufficiently high, nuclear fusion began.

5.

What two effects are balanced when a star such as the Sun is stable?

A stable star exists because the inward pull of gravity is balanced by the outward pressure produced by energy released during fusion.

6.

Explain how gravitational collapse led to fusion reactions and eventually to a stable equilibrium in the Sun.

Gravity caused the nebula to collapse, increasing the temperature until hydrogen nuclei fused into helium. The energy released produced outward pressure which balanced gravity, creating a stable equilibrium.

P8.3d Explain that all bodies emit radiation, and that the intensity and wavelength distribution of any emission depends on their temperatures

1.

What type of radiation is emitted by all bodies?

All bodies emit electromagnetic radiation, mainly infrared radiation.

2.

How does the intensity of radiation emitted by an object change as its temperature increases?

As the temperature of an object increases, the intensity of the radiation emitted increases.

3.

How does the wavelength distribution of emitted radiation change as temperature increases?

As temperature increases, the radiation emitted has a shorter peak wavelength.

4.

Why can hot objects emit a continuous range of electromagnetic radiation?

Hot objects emit a continuous range of electromagnetic radiation because charged particles inside the object are constantly accelerating and vibrating.

5.

Compare the radiation emitted by a hot object with that emitted by a cooler object.

A hot object emits more radiation and a greater proportion of shorter wavelengths than a cooler object.

6.

Explain how the temperature of a body affects both the intensity and wavelength distribution of the radiation it emits.

As temperature increases, both the amount of radiation emitted increases and the peak wavelength becomes shorter, changing the wavelength distribution.

P8.3e Recall the main features of our solar system, including the similarities and distinctions between the planets, their moons, and artificial satellites

1.

Name the eight planets of the Solar System in order from the Sun.

The eight planets in order from the Sun are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

2.

What is meant by a natural satellite?

A natural satellite is an object that naturally orbits a planet, for example the Moon.

3.

What is an artificial satellite?

An artificial satellite is a human-made object placed into orbit around the Earth or another celestial body.

4.

What is a minor planet?

A minor planet is a small body, such as an asteroid, that orbits the Sun but is not classified as a planet.

5.

Compare geostationary and polar orbits used by artificial satellites.

A geostationary satellite remains above the same point on the Earth's surface, whereas a polar satellite passes over the Earth's poles as the Earth rotates beneath it.

6.

Compare planets, natural satellites and artificial satellites in terms of their features and orbits.

Planets orbit the Sun, natural satellites orbit planets naturally, while artificial satellites are launched by humans for purposes such as communication, weather forecasting and navigation.

P8.3f Explain for circular orbits, how the force of gravity can lead to changing velocity of a planet but unchanged speed (qualitative only)

1.

What force keeps a planet moving in orbit around the Sun?

Gravity keeps a planet moving in orbit around the Sun.

2.

Why does a planet moving in a circular orbit have a changing velocity?

A planet has a changing velocity because its direction is constantly changing.

3.

Why can the speed of a planet remain constant even though its velocity changes?

Its speed can remain constant because only the direction changes, not the magnitude of the velocity.

4.

In which direction does the gravitational force act on an orbiting planet?

The gravitational force always acts towards the centre of the orbit.

5.

Explain why velocity changes when the direction of motion changes.

Velocity is a vector quantity, so changing direction means the velocity changes even if the speed stays the same.

6.

Explain how gravity can continuously change the velocity of an orbiting planet without changing its speed.

Gravity continually changes the direction of the planet's motion, producing a changing velocity while the speed remains constant in a circular orbit.

P8.3g Explain how, for a stable orbit, the radius must change if this speed changes (qualitative only)

1.

What is meant by the radius of an orbit?

The radius of an orbit is the distance from the centre of the object being orbited to the orbiting object.

2.

What is meant by a stable orbit?

A stable orbit is one in which an object continues to orbit without crashing into the central body or escaping into space.

3.

What must happen to the orbital radius if the speed of an orbiting object changes?

If the speed of an orbiting object changes, the orbital radius must also change for the orbit to remain stable.

4.

How are orbital speed and orbital radius related for a stable orbit?

For stable orbits, smaller orbital radius means higher orbital speed, while larger orbital radius means lower orbital speed.

5.

Explain why changing the speed of a satellite can cause it to move into a different orbit.

Changing the speed of a satellite changes the balance between gravity and its motion, causing it to move into a different orbit.

6.

Explain qualitatively why a change in orbital speed requires a change in orbital radius for the orbit to remain stable.

A change in orbital speed changes the gravitational force needed for a stable orbit, so the orbital radius changes until a new stable balance is reached.

P8.3h Explain how the temperature of a body is related to the balance between incoming radiation absorbed and radiation emitted; illustrate this balance using everyday examples and the example of the factors which determine the temperature of the Earth

1.

What happens to the temperature of a body when it absorbs radiation faster than it emits radiation?

If a body absorbs radiation faster than it emits radiation, its temperature increases.

2.

What happens to the temperature of a body when it emits radiation faster than it absorbs radiation?

If a body emits radiation faster than it absorbs radiation, its temperature decreases.

3.

When will the temperature of a body remain constant?

The temperature remains constant when the rate of radiation absorbed equals the rate of radiation emitted.

4.

Explain how a hot drink cools in terms of radiation absorbed and emitted.

A hot drink cools because it emits more infrared radiation than it absorbs from its surroundings.

5.

How does the Earth's atmosphere affect electromagnetic radiation travelling to and from the Earth's surface?

The Earth's atmosphere allows most incoming visible radiation from the Sun to reach the surface but absorbs and re-emits some outgoing infrared radiation emitted by the Earth.

6.

Explain how the balance between incoming radiation absorbed and outgoing radiation emitted affects the temperature of the Earth.

The Earth's temperature depends on the balance between incoming solar radiation absorbed and outgoing infrared radiation emitted. If more energy is absorbed than emitted, the Earth warms; if more is emitted than absorbed, it cools.

P8.3i Explain, in qualitative terms, how the differences in velocity, absorption and reflection between different types of waves in solids and liquids can be used both for detection and for exploration of structures which are hidden from direct observation, notably in the Earth's core and in deep water

1.

What are P waves and S waves?

P waves are longitudinal seismic waves that travel through both solids and liquids. S waves are transverse seismic waves that travel only through solids.

2.

How can seismic waves provide information about the internal structure of the Earth?

Seismic waves change speed and direction as they travel through different layers of the Earth, allowing scientists to investigate its internal structure.

3.

Why can the behaviour of P and S waves provide evidence about whether parts of the Earth's interior are solid or liquid?

S waves cannot travel through liquids, while P waves slow down when entering liquids. This provides evidence that the Earth's outer core is liquid.

4.

How can reflection of seismic waves help scientists investigate structures inside the Earth?

Reflected seismic waves allow scientists to identify boundaries between different layers inside the Earth.

5.

How does sonar use reflected sound waves to investigate objects or structures in deep water?

Sonar sends out sound waves and measures the reflected waves to detect underwater objects and measure water depth.

6.

Explain how differences in the velocity, absorption and reflection of waves can be used to investigate the Earth's core and structures in deep water.

Differences in the velocity, absorption and reflection of seismic waves and sound waves allow scientists to investigate the Earth's core and explore structures hidden beneath the Earth's surface or deep underwater.

Physics

Paper 1

P1: Matter

P1.1a Describe how and why the atomic model has changed over time

P1.1b Describe the atom as a positively charged nucleus surrounded by negatively charged electrons, with the nuclear radius much smaller than that of the atom and with almost all of the mass in the nucleus

P1.1c Recall the typical size (order of magnitude) of atoms and small molecules

P1.1d Define density

P1.1e Explain the differences in density between the different states of matter in terms of the arrangements of the atoms and molecules

P1.1f Apply the relationship between density, mass and volume to changes where mass is conserved

P1.2a Describe how mass is conserved when substances melt, freeze, evaporate, condense or sublimate

P1.2b Describe that physical changes differ from chemical changes because the material recovers its original properties if the change is reversed

P1.2c Describe how heating a system will change the energy stored within the system and raise its temperature or produce changes of state

P1.2d Define the term specific heat capacity and distinguish between it and the term specific latent heat

P1.2e Apply the relationship between change in internal energy of a material and its mass, specific heat capacity and temperature change to calculate the energy change involved

P1.2f Apply the relationship between specific latent heat and mass to calculate the energy change involved in a change of state

P1.3a Explain how the motion of the molecules in a gas is related both to its temperature and its pressure

P1.3b Explain the relationship between the temperature of a gas and its pressure at constant volume (qualitative only)

P1.3c Recall that gases can be compressed or expanded by pressure changes and that the pressure produces a net force at right angles to any surface

P1.3d Explain how increasing the volume in which a gas is contained, at constant temperature, can lead to a decrease in pressure

P1.3e Explain how doing work on a gas can increase its temperature

P1.3f Describe a simple model of the Earth's atmosphere and of atmospheric pressure

P1.3g Explain why atmospheric pressure varies with height above the surface of the planet

P1.3h Describe the factors which influence floating and sinking

P1.3i Explain why pressure in a liquid varies with depth and density and how this leads to an upwards force on a partially submerged object

P1.3j Calculate the differences in pressure at different depths in a liquid

P2: Motion

P2.1a Describe how to measure distance and time in a range of scenarios

P2.1b Describe how to measure distance and time and use these to calculate speed

P2.1c Make calculations using ratios and proportional reasoning to convert units and to compute rates

P2.1d Explain the vector–scalar distinction as it applies to displacement and distance, velocity and speed

P2.1e Relate changes and differences in motion to appropriate distance–time and velocity–time graphs; interpret lines and slopes

P2.1f Interpret enclosed area in velocity–time graphs

P2.1g Calculate average speed for non-uniform motion

P2.1h Apply formulae relating distance, time and speed for uniform motion and for motion with uniform acceleration

P2.2a Recall examples of ways in which objects interact

P2.2b Describe how such examples involve interactions between pairs of objects which produce a force on each object

P2.2c Represent forces as vectors

P2.2d Apply Newton's First Law to explain the motion of an object moving with uniform velocity and also an object where the speed and/or direction change

P2.2e Use vector diagrams to illustrate resolution of forces, a net force (resultant force), and equilibrium situations

P2.2f Describe examples of the forces acting on an isolated solid object or system

P2.2g Describe, using free body diagrams, examples where two or more forces lead to a resultant force on an object

P2.2h Describe, using free body diagrams, examples of special case where forces balance to produce a resultant force of zero (qualitative only)

P2.2i Apply Newton's Second Law in calculations relating forces, masses and accelerations

P2.2j Explain that inertia is a measure of how difficult it is to change the velocity of an object and that the inertial mass is defined as the ratio of force over acceleration

P2.2k Define momentum and describe examples of momentum in collisions

P2.2l Apply formulae relating force, mass, velocity and acceleration to explain how the changes involved are inter-related

P2.2m Use the relationship between work done, force, and distance moved along the line of action of the force and describe the energy transfer involved

P2.2n Calculate relevant values of stored energy and energy transfers; convert between newton-metres and joules

P2.2o Explain, with reference to examples, the definition of power as the rate at which energy is transferred

P2.2p Recall and apply Newton's Third Law

P2.2q Explain why an object moving in a circle with a constant speed has a changing velocity (qualitative only)

P2.3a Explain that to stretch, bend or compress an object, more than one force has to be applied

P2.3b Describe the difference between elastic and plastic deformation (distortions) caused by stretching forces

P2.3c Describe the relationship between force and extension for a spring and other simple systems

P2.3d Describe the difference between linear and non-linear relationships between force and extension

P2.3e Calculate a spring constant in linear cases

P2.3f Calculate the work done in stretching

P2.3g Describe that all matter has a gravitational field that causes attraction, and the field strength is much greater for massive objects

P2.3h Define weight, describe how it is measured and describe the relationship between the weight of an object and the gravitational field strength, g

P2.3i Recall the acceleration in free fall

P2.3j Apply formulae relating force, mass and relevant physical constants, including gravitational field strength, g, to explore how changes in these are inter-related

P2.3k Describe examples in which forces cause rotation

P2.3l Define and calculate the moment of a force

P2.3m Explain how levers and gears transmit the rotational effects of forces

P2.3n Recall that the pressure in fluids (gases and liquids) causes a net force at right angles to any surface

P2.3o Use the relationship between the force, the pressure and the area in contact

P3: Electricity

P3.1a Describe that charge is a property of all matter and that there are positive and negative charges

P3.1b Describe the production of static electricity, and sparking, by rubbing surfaces, and evidence that charged objects exert forces of attraction or repulsion on one another when not in contact

P3.1c Explain how transfer of electrons between objects can explain the phenomena of static electricity

P3.1d Explain the concept of an electric field and how it helps to explain the phenomena of static electricity

P3.1e Recall that current is a rate of flow of charge (electrons) and the conditions needed for charge to flow

P3.1f Recall that current has the same value at any point in a single closed loop

P3.1g Recall and use the relationship between quantity of charge, current and time

P3.2a Describe the differences between series and parallel circuits

P3.2b Represent d.c. circuits with the conventions of positive and negative terminals, and the symbols that represent common circuit elements

P3.2c Recall that current, I, depends on both resistance, R, and potential difference, V, and the units in which these are measured

P3.2d Recall and apply the relationship between I, R and V, and that for some resistors the value of R remains constant but that in others it can change as the current changes

P3.2e Explain that for some resistors the value of R remains constant but that in others it can change as the current changes

P3.2f Explain the design and use of circuits to explore such effects