AQA Combined Science: Physics — Recall & Retrieval

6.1.1.1 Energy stores and systems

1.

What is meant by a system in physics?

A system is an object or group of objects being studied and the energy transfers that happen within it.

2.

What happens to energy stores when a system changes?

Energy stores are transferred between different stores when a system changes.

3.

Describe the energy store changes when an object is projected upwards.

A projected object transfers energy from the chemical store of the person/device into the kinetic store of the object. As it rises, kinetic energy decreases and gravitational potential energy increases.

4.

Describe the energy store changes when a moving object hits an obstacle.

A moving object hitting an obstacle transfers energy from the kinetic store to thermal energy stores of the object and surroundings, and possibly elastic potential energy if the object deforms.

5.

Describe the energy store changes when water is heated in an electric kettle.

Water heated in an electric kettle transfers energy electrically from the kettle to the thermal energy store of the water.

6.

Explain why energy cannot be created or destroyed during a system change.

Energy cannot be created or destroyed because of the law of conservation of energy. It can only be transferred between stores.

6.1.1.2 Changes in energy

1.

A 12 kg object gains 720 J of gravitational potential energy when lifted. Calculate the height it was raised. (Use g = 10 N/kg.)

Ep = mgh
720 = 12 × 10 × h
h = 720 ÷ 120
h = 6 m

2.

What does each symbol represent in the equation Ek = ½mv²?

Ek = ½mv²
m = mass in kg
v = velocity in m/s

3.

A car has a mass of 1000 kg and travels at 20 m/s. Calculate its kinetic energy.

Ek = ½ × 1000 × 20²
Ek = 500 × 400
Ek = 200 000 J

4.

A spring stores 0.5 J of elastic potential energy when it is stretched by 0.1m. Calculate the spring constant of the spring.

Ee = ½ke²
0.5 = ½ × k × 0.1²
0.5 = 0.005k
k = 100 N/m

5.

A 5 kg object is lifted 3 m above the ground. Calculate the gravitational potential energy gained by the object. (Gravitational field strength = 10 N/kg)

Ep = mgh
Ep = 5 × 10 × 3
Ep = 150 J

6.

A 2 kg object is lifted 5 m. Calculate the gravitational potential energy gained. (Use g = 10 N/kg.)

Ep = mgh
Ep = 2 × 10 × 5
Ep = 100 J

6.1.1.3 Energy changes in systems

1.

What is meant by the specific heat capacity of a material?

Specific heat capacity is the energy needed to raise the temperature of 1 kg of a substance by 1°C.

2.

What units are used for specific heat capacity?

J/kg°C (joules per kilogram per degree Celsius).

3.

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

E = mcΔT
E = 2 × 500 × 10
E = 10 000 J

4.

Explain what happens to the energy stores when a substance is heated

Heating transfers energy to the thermal energy store of the particles, increasing their kinetic energy and temperature.

5.

A metal block of mass 4 kg absorbs 12 000 J of energy and its temperature increases by 15°C. Calculate the specific heat capacity of the metal.

c = E ÷ (mΔT)
c = 12 000 ÷ (4 × 15)
c = 200 J/kg°C

6.

Describe how an experiment can be carried out to determine the specific heat capacity of a material.

Heat a known mass of the material using an electric heater. Measure the energy supplied and the temperature change. Calculate specific heat capacity using c = E ÷ (mΔT).

6.1.1.4 Power

1.

What is meant by power in physics?

Power is the rate at which energy is transferred.

2.

A device transfers 18 000 J of energy with a power output of 600 W. Calculate the time taken for the energy transfer.

Power = energy transferred ÷ time
600 = 18 000 ÷ t
t = 30 s

3.

What is the unit of power?

Watt (W).

4.

A device transfers 600 J of energy in 30 seconds. Calculate its power.

Power = 600 ÷ 30
Power = 20 W

5.

Explain why a more powerful device transfers energy faster.

A more powerful device transfers energy at a faster rate because it transfers more energy each second.

6.

Compare two devices that transfer the same amount of energy but have different powers.

The device with higher power transfers the same amount of energy in a shorter time.

6.1.2.1 Energy transfers in a system

1.

State the law of conservation of energy.

Energy cannot be created or destroyed; it can only be transferred between stores.

2.

What happens to energy that is not transferred usefully?

Energy that is not transferred usefully is dissipated to the surroundings.

3.

What is meant by wasted energy?

Wasted energy is energy transferred to unwanted stores, usually thermal energy in the surroundings.

4.

Give one example of energy being dissipated to the surroundings.

Friction causing a moving object to heat up.

5.

Explain how lubrication can reduce unwanted energy transfers.

Lubrication reduces friction, so less energy is wasted as thermal energy.

6.

Explain how thermal insulation reduces energy transfer from a building.

Thermal insulation reduces energy transfer by reducing conduction and convection.

6.1.2.2 Efficiency

1.

Can a machine have an efficiency greater than 100%? Explain why.

No. Efficiency cannot be greater than 100% because useful output energy cannot exceed total input energy.

2.

A machine has a useful output energy of 400 J and a total input energy of 800 J. Calculate its efficiency.

Efficiency = useful output ÷ total input × 100
Efficiency = 400 ÷ 800 × 100
Efficiency = 50%

3.

A motor transfers 900 J of useful energy from a total input energy of 1500 J. Calculate its efficiency.

Efficiency = 900 ÷ 1500 × 100
Efficiency = 60%

4.

A device has a useful power output of 80 W and a total power input of 200 W. Calculate its efficiency.

Efficiency = 80 ÷ 200 × 100
Efficiency = 40%

5.

Explain why increasing efficiency is important.

Increasing efficiency reduces wasted energy and saves energy resources.

6.

Give two methods of reducing wasted energy in a system.

Reduce friction using lubrication; improve insulation to reduce thermal energy losses.

6.1.3 National and global energy resources

1.

What is a renewable energy resource?

A renewable energy resource is one that is naturally replaced and will not run out.

2.

What is a non-renewable energy resource?

A non-renewable energy resource is one that is finite and will eventually run out.

3.

Give three examples of renewable energy resources.

Wind, solar, hydroelectric.

4.

Give three examples of non-renewable energy resources.

Coal, oil, natural gas.

5.

Explain why fossil fuels can have a negative environmental impact.

Fossil fuels release carbon dioxide when burned, contributing to climate change and pollution.

6.

Explain why some renewable energy resources are unreliable.

Some renewable resources are unreliable because they depend on weather conditions, such as wind speed and sunlight.

Topic 1 Review

1.

Explain how energy stores change when a system is heated, moved or lifted.

Energy stores change by transferring energy between stores. Heating increases thermal energy stores, lifting increases gravitational potential energy, and movement increases kinetic energy.

2.

Calculate the energy stored in a moving object, stretched spring or raised object using the correct equations.

Kinetic energy: Ek = ½mv². Gravitational potential energy: Ep = mgh. Elastic potential energy: Ee = ½ke².

3.

Explain how specific heat capacity relates energy transferred to temperature change.

Specific heat capacity shows how much energy is needed to increase the temperature of a material. Higher specific heat capacity means more energy is needed for the same temperature rise.

4.

Explain the difference between energy transferred and power.

Energy transferred is the amount of energy moved, while power is the rate of energy transfer.

5.

Explain how energy efficiency can be improved in everyday devices.

Efficiency can be improved by reducing wasted energy, for example through insulation and reducing friction.

6.

Compare renewable and non-renewable energy resources, including their advantages and disadvantages.

Renewable resources are replaced naturally but may be unreliable. Non-renewable resources are reliable but limited and can cause environmental damage.

6.2.1.1 Standard circuit diagram symbols

1.

Draw the circuit symbol for a cell.

Cell: a long line and a short line.

2.

Draw the circuit symbol for a variable resistor.

Variable resistor: resistor symbol with a diagonal arrow through it.

3.

Draw the circuit symbol for a diode.

Diode: triangle/arrow-like symbol with a line showing the direction of current flow.

4.

Draw the circuit symbol for a voltmeter.

Voltmeter: a circle with a V inside.

5.

Draw the circuit symbol for a thermistor

Thermistor: resistor symbol with a diagonal line through it.

6.

Draw the circuit symbol for an ammeter

Ammeter: a circle with an A inside.

6.2.1.2 Electrical charge and current

1.

What is meant by electric current?

Electric current is the rate of flow of electric charge.

2.

A current of 3 A flows through a circuit for 20 seconds. Calculate the charge transferred.

Q = It
Q = 3 × 20
Q = 60 C

3.

A charge of 900 C flows through a circuit in 5 minutes. Calculate the current.

5 minutes = 300 seconds
I = Q ÷ t
I = 900 ÷ 300
I = 3 A

4.

A current of 0.8 A transfers 240 C of charge. Calculate the time taken.

t = Q ÷ I
t = 240 ÷ 0.8
t = 300 s

5.

Explain why a source of potential difference is needed for charge to flow in a circuit.

A potential difference provides energy to charges, causing them to flow through a circuit.

6.

Describe what happens to the current at different points in a single closed loop circuit.

In a single closed loop circuit, the current is the same at all points.

6.2.1.3 Current, resistance and potential difference

1.

A resistor has a resistance of 15 Ω and a current of 2 A flows through it. Calculate the potential difference across the resistor.

V = IR
V = 15 × 2
V = 30 V

2.

A component has a potential difference of 12 V and a resistance of 4 Ω. Calculate the current through the component.

I = V ÷ R
I = 12 ÷ 4
I = 3 A

3.

A circuit has a potential difference of 9 V and a current of 0.3 A. Calculate the resistance.

R = V ÷ I
R = 9 ÷ 0.3
R = 30 Ω

4.

A lamp has a resistance of 60 Ω and operates at a potential difference of 240 V. Calculate the current through the lamp.

I = V ÷ R
I = 240 ÷ 60
I = 4 A

5.

Explain how increasing the resistance of a component affects the current when the potential difference stays the same.

Increasing resistance decreases the current if the potential difference stays the same.

6.

Describe how you could investigate how the length of a wire affects its resistance.

Use wires of different lengths, measure the resistance of each wire while keeping other variables the same, and compare results.

6.2.1.4 Resistors

1.

What is meant by an ohmic conductor?

An ohmic conductor is a component where current is directly proportional to potential difference at constant temperature.

2.

Explain why the resistance of a filament lamp increases as it gets hotter.

The resistance of a filament lamp increases as it gets hotter because the metal ions vibrate more and make it harder for electrons to flow.

3.

Describe how the resistance of a thermistor changes when temperature increases.

A thermistor's resistance decreases as temperature increases.

4.

Describe how the resistance of an LDR changes when light intensity increases.

An LDR's resistance decreases as light intensity increases.

5.

Explain why a diode only allows current to flow in one direction.

A diode only allows current to flow in one direction because it has low resistance in one direction and high resistance in the other.

6.

Describe how I–V graphs can be used to identify whether a component is linear or non-linear.

I–V graphs show whether current is proportional to potential difference. Straight lines show linear components; curved lines show non-linear components.

6.2.2 Series and parallel circuits

1.

What is the difference between a series circuit and a parallel circuit?

A series circuit has components in one loop, while a parallel circuit has components connected across different branches.

2.

Two resistors of 5 Ω and 12 Ω are connected in series. Calculate the total resistance.

Total resistance = 5 + 12
Total resistance = 17 Ω

3.

A series circuit contains resistors of 8 Ω, 6 Ω and 4 Ω. Calculate the total resistance.

Total resistance = 8 + 6 + 4
Total resistance = 18 Ω

4.

Explain how the current behaves in a series circuit.

Current is the same everywhere in a series circuit.

5.

Explain how the potential difference behaves in a parallel circuit.

Potential difference is shared between components in parallel circuits, with the same voltage across each branch.

6.

Explain why adding resistors in parallel decreases the total resistance of a circuit.

Adding resistors in parallel gives more pathways for current, reducing the total resistance.

6.2.3.1 Direct and alternating potential difference

1.

What is the difference between direct potential difference and alternating potential difference?

Direct potential difference provides a constant direction of current flow. Alternating potential difference repeatedly changes direction.

2.

Give the frequency of the UK mains electricity supply.

50 Hz.

3.

Give the approximate potential difference of the UK mains electricity supply.

Approximately 230 V.

4.

Describe the direction of charge flow in a direct current circuit.

Charges flow in one direction only in a direct current circuit.

5.

Explain why mains electricity is described as an alternating supply.

Mains electricity is alternating because the direction of current changes repeatedly.

6.

Give one example of a device that uses a battery supply and one that uses mains electricity.

Battery supply: mobile phone. Mains electricity: kettle.

6.2.3.2 Mains electricity

1.

What are the three wires in a mains cable?

Live wire, neutral wire and earth wire.

2.

What is the purpose of the earth wire?

The earth wire provides a safe path for current during a fault.

3.

What is the colour of the live wire in a UK mains cable?

Brown.

4.

Explain why the live wire is dangerous even when an appliance is switched off.

The live wire remains at a high potential difference and can give an electric shock.

5.

Explain why connecting the live wire to the earth wire is dangerous.

Connecting live and earth creates a large current, which can cause overheating and danger.

6.

Describe what happens during an electrical fault when the earth wire carries a current.

The earth wire carries the fault current, causing the fuse to melt or circuit breaker to switch off.

6.2.4.1 Power

1.

A device operates at a potential difference of 12 V with a current of 3 A. Calculate its power.

P = VI
P = 12 × 3
P = 36 W

2.

A motor has a current of 5 A and a resistance of 8 Ω. Calculate the power transferred.

P = I²R
P = 5² × 8
P = 200 W

3.

A heater transfers energy at a rate of 1500 W when connected to a 230 V supply. Calculate the current.

I = P ÷ V
I = 1500 ÷ 230
I = 6.5 A

4.

A component has a power of 60 W and a current of 2 A. Calculate the resistance.

R = P ÷ I²
R = 60 ÷ 2²
R = 15 Ω

5.

Explain how increasing the current through a device affects its power output.

Increasing current increases power because more energy is transferred each second.

6.

Explain how power is related to energy transferred over time.

Power is the rate of energy transfer: Power = energy transferred ÷ time.

6.2.4.2 Energy transfers in everyday appliances

1.

A 1000 W kettle is used for 180 seconds. Calculate the energy transferred.

E = Pt
E = 1000 × 180
E = 180 000 J

2.

A device transfers 7200 J of energy in 120 seconds. Calculate its power.

P = E ÷ t
P = 7200 ÷ 120
P = 60 W

3.

An appliance transfers 5000 J of energy using a charge flow of 25 C. Calculate the potential difference.

V = E ÷ Q
V = 5000 ÷ 25
V = 200 V

4.

A battery-powered device transfers 240 J of energy at a potential difference of 6 V. Calculate the charge transferred.

Q = E ÷ V
Q = 240 ÷ 6
Q = 40 C

5.

Describe how electrical appliances transfer energy from an electrical supply to useful energy stores.

Appliances transfer electrical energy into useful energy stores, such as thermal, kinetic or light energy stores.

6.

Explain why appliances with higher power ratings transfer more energy each second.

Higher power appliances transfer more energy every second.

6.2.4.3 The National Grid

1.

What is the National Grid?

The National Grid is a system of cables and transformers used to transfer electrical energy around the country.

2.

What is the purpose of a step-up transformer?

A step-up transformer increases potential difference for efficient transmission.

3.

What is the purpose of a step-down transformer?

A step-down transformer decreases potential difference for safe use in homes.

4.

Explain why increasing the potential difference reduces energy losses in transmission cables.

Higher potential difference reduces current, reducing energy losses in cables.

5.

Describe how electricity is transferred from power stations to homes.

Electricity travels from power stations through transmission cables, then through transformers to homes.

6.

Explain why the National Grid is an efficient method of transferring electrical energy.

The National Grid is efficient because it transfers energy at high potential differences, reducing wasted energy.

Topic 2 Review

1.

Explain how charge, current and time are related in an electrical circuit.

Charge, current and time are related by Q = It.

2.

Calculate the current in a circuit where 480 C of charge flows in 2 minutes.

Q = 480 C, t = 120 s
I = Q ÷ t
I = 480 ÷ 120
I = 4 A

3.

Explain the differences between series and parallel circuits.

Series circuits have one pathway and the same current. Parallel circuits have multiple pathways and the same potential difference across branches.

4.

A heater has a power rating of 2000 W and operates for 5 minutes. Calculate the energy transferred.

E = Pt
E = 2000 × 300
E = 600 000 J

5.

Explain how thermistors and LDRs are used in electrical circuits.

Thermistors change resistance with temperature and LDRs change resistance with light intensity, allowing circuits to respond to changes.

6.

Describe how the National Grid transfers electrical energy efficiently from power stations to consumers.

The National Grid uses high potential differences and transformers to transfer electrical energy efficiently from power stations to consumers.

6.3.1.1 Density of materials

1.

What is meant by density?

Density is the mass per unit volume of a substance.

2.

A metal block has a mass of 2 kg and a volume of 0.0005 m³. Calculate its density.

Density = mass ÷ volume
Density = 2 ÷ 0.0005
Density = 4000 kg/m³

3.

A liquid has a density of 800 kg/m³ and a volume of 0.002 m³. Calculate its mass.

Mass = density × volume
Mass = 800 × 0.002
Mass = 1.6 kg

4.

A sample has a mass of 5 kg and a density of 2500 kg/m³. Calculate its volume.

Volume = mass ÷ density
Volume = 5 ÷ 2500
Volume = 0.002 m³

5.

Explain why solids usually have a higher density than gases using the particle model.

Solids usually have higher density than gases because their particles are packed closely together, while gas particles are spread out.

6.

Describe how the arrangement and movement of particles differs between solids, liquids and gases.

Solid particles are closely packed and vibrate around fixed positions. Liquid particles are close together but can move around each other. Gas particles are far apart and move randomly at high speeds.

Required practical activity: Measuring density

1.

Describe how you could measure the density of a regularly shaped solid object.

Measure the mass using a balance. Measure the dimensions using a ruler or callipers. Calculate volume and use density = mass ÷ volume.

2.

Explain how you could find the volume of an irregular solid object.

Use water displacement in a measuring cylinder to find the volume of an irregular object.

3.

A student measures a metal cube with sides of 5 cm. Calculate the volume of the cube.

Volume = length × width × height
Volume = 5 × 5 × 5
Volume = 125 cm³

4.

A cube has a mass of 0.75 kg and a volume of 0.0003 m³. Calculate its density.

Density = mass ÷ volume
Density = 0.75 ÷ 0.0003
Density = 2500 kg/m³

5.

Name suitable equipment that could be used to measure the dimensions of a small solid object accurately.

Vernier callipers or a micrometer.

6.

Explain why displacement is used to measure the volume of irregular objects.

Displacement is used because irregular objects do not have simple shapes, so their volume cannot be calculated using dimensions.

6.3.1.2 Changes of state

1.

Name the changes of state from solid to liquid and liquid to gas.

Solid to liquid: melting. Liquid to gas: boiling or evaporation.

2.

Explain why mass is conserved when a substance changes state.

Mass is conserved because no particles are created or destroyed.

3.

Explain why melting is a physical change rather than a chemical change.

Melting is physical because the substance remains the same and no new substance is formed.

4.

Describe what happens to particles when a substance melts.

Particles gain energy, vibrate more and become able to move around each other.

5.

Explain the difference between evaporation and boiling.

Evaporation occurs at the surface and can happen below boiling point. Boiling occurs throughout a liquid at a fixed temperature.

6.

Describe what happens to the energy stored in particles during a change of state.

Energy is transferred to particles, increasing their potential energy during a change of state.

6.3.2.1 Internal energy

1.

What is meant by internal energy?

Internal energy is the total energy stored by particles in a system.

2.

What two types of energy make up the internal energy of a system?

Kinetic energy and potential energy.

3.

Explain how heating affects the energy stored by particles.

Heating increases the kinetic energy of particles and may increase potential energy during changes of state.

4.

Explain why increasing the temperature of a substance increases its internal energy.

Higher temperature means particles have greater kinetic energy, increasing internal energy.

5.

Describe the difference between the kinetic energy and potential energy of particles.

Kinetic energy is energy due to particle movement. Potential energy is stored due to particle positions and forces between particles.

6.

Explain how a change of state can occur without a temperature change.

A change of state can occur without temperature change because energy changes the arrangement of particles rather than increasing kinetic energy.

6.3.2.2 Temperature changes in a system and specific heat capacity

1.

A 2 kg block has a specific heat capacity of 500 J/kg°C. It is heated by 20°C. Calculate the energy transferred.

E = mcΔT
E = 2 × 500 × 20
E = 20 000 J

2.

A material receives 12 000 J of energy. Its mass is 3 kg and its specific heat capacity is 400 J/kg°C. Calculate the temperature change.

ΔT = E ÷ mc
ΔT = 12 000 ÷ (3 × 400)
ΔT = 10°C

3.

A 5 kg object is heated by 10°C using 20 000 J of energy. Calculate its specific heat capacity.

c = E ÷ (mΔT)
c = 20 000 ÷ (5 × 10)
c = 400 J/kg°C

4.

Explain what is meant by specific heat capacity.

Specific heat capacity is the energy required to raise the temperature of 1 kg of a substance by 1°C.

5.

Explain why different materials require different amounts of energy to increase their temperature by the same amount.

Different materials have different particle structures and require different amounts of energy to increase particle kinetic energy.

6.

Describe how mass affects the temperature change of a substance when the same energy is supplied.

A larger mass requires more energy, so the temperature change is smaller when the same energy is supplied.

6.3.2.3 Changes of state and specific latent heat

1.

What is meant by latent heat?

Latent heat is energy transferred to change the state of a substance without changing its temperature.

2.

Explain why the temperature stays constant during a change of state.

Temperature stays constant because energy is used to overcome forces between particles rather than increase kinetic energy.

3.

A 2 kg sample melts and requires 680 000 J of energy. Calculate its specific latent heat of fusion.

E = mL
680 000 = 2 × L
L = 340 000 J/kg

4.

A substance has a specific latent heat of vaporisation of 2 000 000 J/kg. Calculate the energy needed to vaporise 0.5 kg.

E = mL
E = 0.5 × 2 000 000
E = 1 000 000 J

5.

Explain the difference between specific latent heat of fusion and specific latent heat of vaporisation.

Specific latent heat of fusion is energy needed to melt 1 kg of a substance. Specific latent heat of vaporisation is energy needed to boil 1 kg of a substance.

6.

Explain what happens to the internal energy of particles during melting.

During melting, particles gain potential energy as forces between particles are overcome.

6.3.3.1 Particle motion in gases

1.

Describe the movement of particles in a gas.

Gas particles move randomly at high speeds in all directions.

2.

Explain how temperature affects the kinetic energy of gas particles.

Increasing temperature increases the kinetic energy of gas particles.

3.

Explain why increasing the temperature of a gas increases its pressure when volume is constant.

Hotter particles move faster and collide more frequently and with greater force with the container walls, increasing pressure.

4.

A gas is heated while kept in a fixed container. Explain what happens to the particles.

The particles gain kinetic energy, move faster and collide more often with the container walls.

5.

Explain why gas particles exert pressure on the walls of a container.

Gas particles collide with the walls of the container, creating pressure.

6.

Describe the relationship between temperature, particle motion and gas pressure.

Higher temperature causes faster particle movement, leading to more frequent and forceful collisions and increased pressure.

Topic 3 Review

1.

Calculate the density of an object with a mass of 4 kg and a volume of 0.002 m³.

Density = mass ÷ volume
Density = 4 ÷ 0.002
Density = 2000 kg/m³

2.

Explain the particle model differences between solids, liquids and gases.

Solids have particles closely packed and vibrating. Liquids have particles close together that can move. Gases have particles spread out and moving randomly.

3.

Explain how energy is transferred during heating and changes of state.

Heating transfers energy to particles, increasing kinetic energy or changing particle arrangement during changes of state.

4.

Calculate the energy needed to heat a substance using its mass, specific heat capacity and temperature change.

E = mcΔT.

5.

Calculate the energy needed for a change of state using specific latent heat.

E = mL.

6.

Explain how the temperature of a gas affects its pressure when the volume is unchanged.

Increasing gas temperature increases particle kinetic energy, causing more frequent and forceful collisions with container walls, increasing pressure.

6.4.1.3 The development of the model of the atom

1.

Describe the model of the atom before the discovery of the electron.

Before electrons were discovered, atoms were thought to be solid spheres with no internal structure.

2.

Explain how the discovery of electrons changed the model of the atom.

The discovery of electrons showed that atoms contained smaller negatively charged particles, changing the model of the atom.

3.

Describe the plum pudding model of the atom.

The plum pudding model described atoms as a sphere of positive charge with negative electrons embedded inside.

4.

Explain why the results of the alpha particle scattering experiment caused the nuclear model to replace the plum pudding model.

The alpha particle scattering experiment showed that atoms contain a small, dense, positively charged nucleus and that most of the atom is empty space.

5.

State the main difference between the plum pudding model and the nuclear model of the atom.

The plum pudding model had electrons spread throughout the atom, while the nuclear model had electrons orbiting a small central nucleus.

6.

Explain how scientific models can change when new experimental evidence is discovered.

Scientific models change when new experimental evidence provides information that cannot be explained by the current model.

6.4.2.1 Radioactive decay and nuclear radiation

1.

What is radioactive decay?

Radioactive decay is the random process where an unstable nucleus emits radiation and changes into a more stable nucleus.

2.

Why do some atomic nuclei undergo radioactive decay?

Some nuclei undergo radioactive decay because they are unstable due to an imbalance of protons and neutrons.

3.

What is meant by activity of a radioactive source?

Activity is the rate at which unstable nuclei decay.

4.

Name the unit used to measure radioactive activity.

Becquerel (Bq).

5.

Describe the composition of an alpha particle, beta particle and gamma ray.

Alpha: two protons and two neutrons. Beta: a high-energy electron. Gamma: electromagnetic radiation.

6.

Compare alpha, beta and gamma radiation in terms of penetration and ionising power.

Alpha has the lowest penetration but highest ionising power. Beta has medium penetration and ionising power. Gamma has the highest penetration but lowest ionising power.

6.4.2.2 Nuclear equations

1.

What happens to the mass number and atomic number during alpha decay?

During alpha decay, the mass number decreases by 4 and the atomic number decreases by 2.

2.

What happens to the mass number and atomic number during beta decay?

During beta decay, the mass number stays the same and the atomic number increases by 1.

3.

Complete the nuclear equation: ²³⁸₉₂U → ⁴₂He + ______

²³⁸₉₂U → ⁴₂He + ²³⁴₉₀Th

4.

Complete the nuclear equation: ¹⁴₆C → ⁰₋₁e + ______

¹⁴₆C → ⁰₋₁e + ¹⁴₇N

5.

Explain why gamma radiation does not change the mass number or atomic number of a nucleus.

Gamma radiation is energy released from the nucleus and does not contain mass or charge, so the mass number and atomic number remain unchanged.

6.

A nucleus emits an alpha particle. Explain how the nucleus changes after the decay.

The nucleus loses two protons and two neutrons, so the mass number decreases by 4 and the atomic number decreases by 2.

6.4.2.3 Half-lives and the random nature of radioactive decay

1.

What is meant by the half-life of a radioactive isotope?

Half-life is the time taken for the number of undecayed nuclei or activity of a radioactive sample to halve.

2.

Explain why radioactive decay is described as a random process.

Radioactive decay is random because it is impossible to predict when a particular nucleus will decay.

3.

A radioactive sample has a count rate of 800 counts per minute. After one half-life, what is the count rate?

After one half-life:
800 ÷ 2 = 400 counts per minute

4.

A sample has an initial activity of 1600 Bq and a half-life of 5 years. Calculate its activity after 15 years.

15 years = 3 half-lives
1600 → 800 → 400 → 200
Activity = 200 Bq

5.

A radioactive isotope has a half-life of 10 days. Explain how the number of undecayed nuclei changes over time.

The number of undecayed nuclei decreases by half during each half-life.

6.

Explain why half-life can be used to identify the stability of a radioactive isotope.

A shorter half-life means a radioactive isotope is less stable and decays more quickly.

6.4.2.4 Radioactive contamination

1.

What is meant by radioactive contamination?

Radioactive contamination is when radioactive material gets onto or inside an object.

2.

Explain why radioactive contamination is dangerous.

It is dangerous because radioactive materials can emit ionising radiation that damages cells.

3.

What is irradiation?

Irradiation is exposure to radiation from a radioactive source.

4.

Explain the difference between contamination and irradiation.

Contamination involves radioactive material being present on or inside something. Irradiation is only exposure to radiation.

5.

Explain why an object that has been irradiated does not become radioactive.

An irradiated object does not become radioactive because it has not gained radioactive material.

6.

Explain why research into the effects of radiation should be shared and checked by other scientists.

Scientific research should be shared and checked to ensure results are reliable and accurate.

Topic 4 Review

1.

Explain how evidence from experiments changed the atomic model over time.

Evidence from experiments changed the atomic model from a solid sphere to models containing electrons and a nucleus.

2.

Compare the properties and uses of alpha, beta and gamma radiation.

Alpha radiation has high ionising power and low penetration. Beta has medium ionising power and penetration. Gamma has low ionising power and high penetration.

3.

Complete a nuclear equation showing alpha or beta decay.

Alpha decay: mass number decreases by 4 and atomic number decreases by 2. Beta decay: atomic number increases by 1 while mass number stays the same.

4.

Calculate the remaining activity of a radioactive source after several half-lives.

Each half-life halves the activity of a radioactive source.

5.

Explain the difference between radioactive contamination and irradiation.

Contamination is radioactive material on or inside an object. Irradiation is exposure to radiation without radioactive material being transferred.

6.

Evaluate why radioactive sources must be carefully controlled when used.

Radioactive sources must be controlled because ionising radiation can damage living cells and cause harm if not used safely.

6.5.1.1 Scalar and vector quantities

1.

State whether distance is a scalar or vector quantity.

Distance is a scalar quantity.

2.

State whether displacement is a scalar or vector quantity.

Displacement is a vector quantity.

3.

State whether speed is a scalar or vector quantity.

Speed is a scalar quantity.

4.

State whether velocity is a scalar or vector quantity.

Velocity is a vector quantity.

5.

State whether force is a scalar or vector quantity.

Force is a vector quantity.

6.

Explain the difference between a scalar quantity and a vector quantity.

A scalar quantity has magnitude only. A vector quantity has magnitude and direction.

6.5.1.2 Contact and non-contact forces

1.

Give two examples of contact forces.

Friction and air resistance.

2.

Give two examples of non-contact forces.

Gravity and magnetic forces.

3.

Explain the difference between contact and non-contact forces.

Contact forces require objects to touch. Non-contact forces act over a distance.

4.

Describe the interaction between two objects when friction acts.

Friction acts between surfaces in contact and opposes motion.

5.

Describe the interaction between two magnets that repel each other.

Two magnets with the same poles repel because their magnetic fields interact.

6.

Explain why force is a vector quantity.

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

6.5.1.3 Gravity

1.

A box has a mass of 8 kg. Calculate its weight if the gravitational field strength is 10 N/kg.

Weight = mass × gravitational field strength
Weight = 8 × 10
Weight = 80 N

2.

A suitcase weighs 180 N on a planet where the gravitational field strength is 9 N/kg. Calculate its mass.

Mass = weight ÷ gravitational field strength
Mass = 180 ÷ 9
Mass = 20 kg

3.

Explain the difference between mass and weight.

Mass is the amount of matter in an object and stays constant. Weight is the force caused by gravity and can change depending on the gravitational field strength.

4.

Describe where the weight of an object acts.

Weight acts from the centre of mass of an object.

5.

Explain why an astronaut's mass stays the same but their weight changes on the Moon.

An astronaut's mass stays the same because the amount of matter does not change, but their weight changes because the Moon has a weaker gravitational field.

6.

Name the instrument used to measure weight.

A Newton meter (spring balance).

6.5.1.4 Resultant forces

1.

Two forces of 18 N and 7 N act in the same direction. Calculate the resultant force.

Resultant force = 18 + 7
Resultant force = 25 N

2.

Two forces of 25 N and 9 N act in opposite directions. Calculate the resultant force.

Resultant force = 25 − 9
Resultant force = 16 N

3.

Explain what is meant by a resultant force.

A resultant force is the overall force acting on an object after combining all forces.

4.

Describe what happens when the resultant force on an object is zero.

If the resultant force is zero, the object remains at rest or continues at constant velocity.

5.

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

Free-body diagram: upward reaction force from the table and downward weight force.

6.

Describe how a vector diagram can be used to determine a resultant force. (HT)

A vector diagram uses arrows representing forces. The combined length and direction show the resultant force.

6.5.2 Work done and energy transfer

1.

A force of 45 N moves an object 6 m. Calculate the work done.

Work done = force × distance
Work done = 45 × 6
Work done = 270 J

2.

A machine does 720 J of work using a force of 90 N. Calculate the distance moved.

Distance = work done ÷ force
Distance = 720 ÷ 90
Distance = 8 m

3.

A force of 15 N moves an object 12 m. Calculate the work done.

Work done = 15 × 12
Work done = 180 J

4.

Explain what happens to energy when work is done.

Work done transfers energy from one energy store to another.

5.

Explain why work done against friction causes an increase in temperature.

Work done against friction transfers energy to thermal energy stores, increasing temperature.

6.

Convert 650 N m into joules.

650 N m = 650 J

6.5.3 Forces and elasticity

1.

A spring has a spring constant of 300 N/m and extends by 0.08 m. Calculate the force applied.

Force = spring constant × extension
Force = 300 × 0.08
Force = 24 N

2.

A spring extends by 0.25 m when a force of 100 N is applied. Calculate the spring constant.

Spring constant = force ÷ extension
k = 100 ÷ 0.25
k = 400 N/m

3.

A spring has a spring constant of 180 N/m and is stretched by 0.20 m. Calculate the elastic potential energy stored.

Ee = ½ke²
Ee = ½ × 180 × 0.20²
Ee = 3.6 J

4.

Explain the difference between elastic and inelastic deformation.

Elastic deformation is reversible. Inelastic deformation is permanent.

5.

Explain what happens if the limit of proportionality is exceeded.

The spring will no longer return to its original shape and becomes permanently stretched.

6.

Describe how you would investigate the relationship between force and extension for a spring in the required practical.

Apply different forces to a spring, measure the extension each time, and plot a graph of force against extension.

6.5.4.1.1 Distance and displacement

1.

Explain the difference between distance and displacement.

Distance is the total path travelled. Displacement is the straight-line distance in a stated direction from the starting point.

2.

A runner completes one lap of a 400 m track and finishes where they started. State the distance travelled and displacement.

Distance = 400 m. Displacement = 0 m.

3.

Give an example of a vector quantity used to describe motion.

Velocity.

4.

Give an example of a scalar quantity used to describe motion.

Speed.

5.

Describe how displacement should always be stated.

Displacement should include both size and direction.

6.

Explain why displacement can never be greater than distance travelled.

Displacement is the shortest distance between two points, so it cannot be greater than distance travelled.

6.5.4.1.2 Speed

1.

A cyclist travels 5400 m in 300 s. Calculate the average speed.

Speed = distance ÷ time
Speed = 5400 ÷ 300
Speed = 18 m/s

2.

A car travels at 20 m/s for 45 s. Calculate the distance travelled.

Distance = speed × time
Distance = 20 × 45
Distance = 900 m

3.

A runner covers 600 m at an average speed of 5 m/s. Calculate the time taken.

Time = distance ÷ speed
Time = 600 ÷ 5
Time = 120 s

4.

State the typical speed of a person walking.

Typical walking speed = 1.5 m/s.

5.

State the typical speed of sound in air.

Speed of sound in air = approximately 340 m/s.

6.

Explain why average speed is used for most journeys.

Average speed is used because most journeys involve changing speeds.

6.5.4.1.3 Velocity

1.

Explain the difference between speed and velocity.

Speed has magnitude only. Velocity has magnitude and direction.

2.

Give an example where an object has constant speed but changing velocity. (HT)

An object travelling around a circular path has constant speed but changing velocity because direction changes.

3.

Explain why velocity is a vector quantity.

Velocity is a vector because it includes direction.

4.

State whether velocity or speed includes direction.

Velocity includes direction.

5.

Describe the velocity of a car travelling north at 15 m/s.

The car has a velocity of 15 m/s north.

6.

Explain why travelling in a circle involves changing velocity. (HT)

Travelling in a circle involves changing direction, so velocity changes.

6.5.4.1.4 The distance–time relationship

1.

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

The gradient represents speed.

2.

Describe the appearance of a distance–time graph for a stationary object.

A stationary object has a horizontal line.

3.

Describe the appearance of a distance–time graph for an object moving at constant speed.

A constant speed object has a straight line with constant gradient.

4.

Explain what a steeper gradient on a distance–time graph shows.

A steeper gradient shows a greater speed.

5.

Calculate the speed of an object if the gradient of its distance–time graph is 6 m/s.

Speed = 6 m/s.

6.

Explain how a tangent can be used to estimate instantaneous speed. (HT)

A tangent shows the gradient at a specific point to calculate instantaneous speed.

6.5.4.1.5 Acceleration

1.

A car increases its velocity from 8 m/s to 28 m/s in 5 s. Calculate its acceleration.

Acceleration = change in velocity ÷ time
Acceleration = (28 − 8) ÷ 5
Acceleration = 4 m/s²

2.

An object accelerates at 4 m/s² for 7 s from rest. Calculate its final velocity.

Final velocity = acceleration × time
Final velocity = 4 × 7
Final velocity = 28 m/s

3.

A car accelerates from 12 m/s to 28 m/s over 80 m. Calculate its acceleration.

v² = u² + 2as
28² = 12² + 2 × a × 80
784 = 144 + 160a
a = 4 m/s²

4.

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

The gradient of a velocity–time graph represents acceleration.

5.

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

The area under a velocity–time graph represents distance travelled.

6.

Explain what terminal velocity means.

Terminal velocity is when the resultant force becomes zero and an object falls at a constant velocity.

6.5.4.2.1 Newton's First Law

1.

State what happens to an object if the resultant force acting on it is zero.

An object remains stationary or continues moving at constant velocity if the resultant force is zero.

2.

Explain why a car travelling at constant speed has zero resultant force.

Constant speed means forces are balanced and resultant force is zero.

3.

Explain why an object changes velocity only when a resultant force acts.

A resultant force causes acceleration, changing velocity.

4.

Define inertia. (HT)

Inertia is the tendency of an object to resist changes in motion.

5.

Give an example of Newton's First Law in everyday life.

Passengers move forward when a car brakes because their bodies continue moving due to inertia.

6.

Explain why passengers move forwards when a car brakes suddenly.

Passengers move forward because their bodies continue moving while the car slows down.

6.5.4.2.2 Newton's Second Law

1.

A force of 180 N acts on a mass of 12 kg. Calculate its acceleration.

Force = mass × acceleration
Force = 12 × 3.6
Force = 43.2 N

2.

A 5 kg object accelerates at 3.6 m/s². Calculate the resultant force.

Force = 5 × 3.6
Force = 18 N

3.

A force of 48 N causes an object to accelerate at 6 m/s². Calculate its mass.

Mass = force ÷ acceleration
Mass = 48 ÷ 6
Mass = 8 kg

4.

Explain how increasing mass affects acceleration for a constant force.

Increasing mass decreases acceleration if the force stays constant.

5.

Describe the required practical investigating force, mass and acceleration.

Investigate how changing force or mass affects acceleration using a trolley system and measure acceleration with light gates or motion sensors.

6.

Explain what inertial mass means. (HT)

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

6.5.4.2.3 Newton's Third Law

1.

State Newton's Third Law.

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

2.

Give an example of an action–reaction force pair.

A rocket pushes gases down and the gases push the rocket upwards.

3.

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

Action and reaction forces act on different objects, so they do not cancel.

4.

Describe the forces acting when a person pushes against a wall.

The person pushes the wall and the wall pushes back with an equal force.

5.

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

A rocket moves upwards because gases are pushed down, creating an upward reaction force.

6.

Explain why recoil occurs when firing a gun.

Recoil occurs because the object pushing a projectile experiences an equal and opposite force.

6.5.4.3.1 Stopping distance

1.

Explain what is meant by stopping distance.

Stopping distance is the total distance travelled before a vehicle stops.

2.

State the two parts of stopping distance.

Thinking distance and braking distance.

3.

Explain why stopping distance increases as speed increases.

Higher speed increases kinetic energy, so more distance is needed to stop.

4.

Describe how thinking distance differs from braking distance.

Thinking distance is travelled before braking begins. Braking distance is travelled while slowing down.

5.

Explain why doubling speed more than doubles braking distance.

Braking distance increases more than proportionally because kinetic energy increases with speed squared.

6.

Explain why understanding stopping distance is important for road safety.

Understanding stopping distance helps drivers maintain safe distances.

6.5.4.3.2 Reaction time

1.

State the typical range of human reaction times.

Typical reaction time is about 0.2–0.9 seconds.

2.

Describe one method used to measure reaction time.

Use a ruler drop test or computer reaction timer.

3.

State two factors that increase reaction time.

Alcohol, tiredness and distractions increase reaction time.

4.

Explain why distractions increase thinking distance.

Distractions delay the response, increasing thinking distance.

5.

Explain how alcohol affects reaction time.

Alcohol slows the nervous system, increasing reaction time.

6.

Describe how the reaction time required practical could be carried out.

Measure reaction times under different conditions and compare results.

6.5.4.3.3 Factors affecting braking distance

1.

Explain how wet roads affect braking distance.

Wet roads reduce friction, increasing braking distance.

2.

Explain how icy roads affect braking distance.

Icy roads greatly reduce friction, increasing braking distance.

3.

Explain why worn tyres increase braking distance.

Worn tyres provide less grip, increasing braking distance.

4.

Explain why worn brakes increase braking distance.

Worn brakes produce less braking force, increasing stopping distance.

5.

Explain why braking distance increases with speed.

Higher speed increases kinetic energy, requiring more distance to stop.

6.

Describe two ways drivers can reduce stopping distance.

Reduce speed and maintain tyres and brakes properly.

6.5.4.3.4 Factors affecting braking distance 2

1.

Explain why the brakes become hot when a vehicle stops.

Brakes become hot because kinetic energy is transferred to thermal energy through friction.

2.

Explain why a larger braking force causes a greater deceleration.

A larger braking force causes a greater deceleration.

3.

Explain why excessive braking can cause loss of control.

Excessive braking can cause tyres to lose grip and the vehicle to skid.

4.

Explain why brakes may overheat after repeated heavy braking.

Repeated braking transfers large amounts of energy to thermal energy stores, causing overheating.

5.

Estimate the braking force needed to stop a vehicle of known mass and deceleration. (HT)

Braking force = mass × deceleration.

6.

Explain why kinetic energy increases rapidly as speed increases.

Kinetic energy increases rapidly because Ek = ½mv².

6.5.5.1 Momentum (HT only)

1.

A 1200 kg car travels at 18 m/s. Calculate its momentum.

Momentum = mass × velocity
Momentum = 1200 × 18
Momentum = 21 600 kg m/s

2.

A ball has a momentum of 16 kg m/s and a mass of 0.8 kg. Calculate its velocity.

Velocity = momentum ÷ mass
Velocity = 16 ÷ 0.8
Velocity = 20 m/s

3.

A cyclist has a mass of 75 kg and a momentum of 450 kg m/s. Calculate the velocity.

Velocity = momentum ÷ mass
Velocity = 450 ÷ 75
Velocity = 6 m/s

4.

Explain what is meant by momentum.

Momentum is the product of mass and velocity.

5.

State the units of momentum.

kg m/s.

6.

Explain why a faster object has greater momentum if its mass stays the same.

A faster object has greater momentum because velocity increases.

6.5.5.2 Conservation of momentum (HT only)

1.

A 2 kg trolley moving at 4 m/s collides with a stationary trolley and they stick together. Calculate their combined velocity after the collision.

Total momentum before collision = 2 × 4 = 8 kg m/s
Combined mass = 2 + 2 = 4 kg
Velocity = 8 ÷ 4
Velocity = 2 m/s

2.

Explain what is meant by conservation of momentum.

Conservation of momentum means total momentum before and after an event remains constant.

3.

State the condition required for momentum to be conserved.

The system must be closed with no external forces acting.

4.

Explain why momentum is conserved during a collision in a closed system.

Momentum is conserved because forces inside the system are equal and opposite.

5.

Describe one experiment used to investigate conservation of momentum.

Use trolleys on a track, measure masses and velocities before and after collision, and compare momentum.

6.

Explain why momentum is useful when analysing collisions.

Momentum helps analyse collisions by showing how motion changes during interactions.

Topic 5 Review

1.

A force of 250 N acts on an object with a mass of 50 kg. Calculate its acceleration.

Force = 250 N, mass = 50 kg
Acceleration = force ÷ mass = 250 ÷ 50 = 5 m/s²

2.

A spring with a spring constant of 400 N/m extends by 0.12 m. Calculate the elastic potential energy stored.

Ee = ½ke²
Ee = ½ × 400 × 0.12²
Ee = 2.88 J

3.

A car travels 180 m in 9 s. Calculate its average speed.

Speed = distance ÷ time
Speed = 180 ÷ 9
Speed = 20 m/s

4.

A force of 80 N moves an object 15 m. Calculate the work done.

Work done = force × distance
Work done = 80 × 15
Work done = 1200 J

5.

Explain the difference between thinking distance and braking distance.

Thinking distance is travelled before braking begins. Braking distance is travelled while slowing down.

6.

Explain how Newton's three laws can be used to describe the motion of a car.

Newton's First Law explains why a car stays at constant velocity with balanced forces. Newton's Second Law explains how force, mass and acceleration are related when the car speeds up or slows down. Newton's Third Law explains the equal and opposite forces between the car's tyres and the road.

6.6.1.1 Transverse and longitudinal waves

1.

State one difference between a transverse wave and a longitudinal wave.

Transverse waves vibrate perpendicular to the direction of energy transfer. Longitudinal waves vibrate parallel to the direction of energy transfer.

2.

Give one example of a transverse wave.

Light waves.

3.

Give one example of a longitudinal wave.

Sound waves.

4.

What are the regions of high and low pressure in a longitudinal wave called?

High-pressure regions are compressions and low-pressure regions are rarefactions.

5.

Explain why sound cannot travel through a vacuum.

Sound cannot travel through a vacuum because there are no particles to transfer the vibrations.

6.

Explain why ripples on water transfer energy but not water across the surface.

Water ripples transfer energy across the surface but the water particles only move up and down.

6.6.1.2 Properties of waves

1.

Define amplitude.

Amplitude is the maximum displacement of a point on a wave from its rest position.

2.

Define wavelength.

Wavelength is the distance between two corresponding points on consecutive waves.

3.

Define frequency.

Frequency is the number of waves passing a point each second.

4.

A wave has a frequency of 8 Hz. Calculate its period.

Period = 1 ÷ frequency
Period = 1 ÷ 8
Period = 0.125 s

5.

A wave travels at 24 m/s and has a wavelength of 6 m. Calculate its frequency.

Wave speed = frequency × wavelength
Frequency = speed ÷ wavelength
Frequency = 24 ÷ 6
Frequency = 4 Hz

6.

Describe how you could measure the speed of sound in air.

Measure the distance travelled by sound and measure the time taken. Calculate speed using speed = distance ÷ time.

6.6.2.1 Types of electromagnetic waves

1.

List the electromagnetic spectrum in order from longest wavelength to shortest wavelength.

Radio waves → microwaves → infrared → visible light → ultraviolet → X-rays → gamma rays.

2.

Which part of the electromagnetic spectrum is visible to the human eye?

Visible light.

3.

State one similarity shared by all electromagnetic waves.

All electromagnetic waves transfer energy and travel at the same speed in a vacuum.

4.

State one example of energy being transferred by an electromagnetic wave.

Infrared transferring thermal energy.

5.

Which electromagnetic wave has the highest frequency?

Gamma rays.

6.

Explain the relationship between wavelength and frequency across the electromagnetic spectrum.

Higher frequency electromagnetic waves have shorter wavelengths.

6.6.2.2 Properties of electromagnetic waves 1

1.

What can happen to electromagnetic waves when they meet a different material?

Electromagnetic waves can be reflected, refracted, absorbed or transmitted.

2.

Explain why light changes direction when it enters a different medium.

Light changes direction because its speed changes when it enters a different medium.

3.

What is meant by refraction?

Refraction is the change in direction of a wave caused by a change in speed when it enters a different material.

4.

Explain why waves slow down when travelling through some materials.

Waves slow down because they interact with particles in the material.

5.

Describe how a ray diagram shows refraction.

A ray diagram shows the incident ray, normal line and refracted ray.

6.

In the required practical investigating infrared radiation, what variable is changed and what is measured?

The variable changed is the distance from the infrared source. The variable measured is the temperature increase.

6.6.2.3 Properties of electromagnetic waves 2

1.

Which electromagnetic waves are ionising?

Ultraviolet, X-rays and gamma rays are ionising.

2.

Which electromagnetic wave is produced by changes in the nucleus of an atom?

Gamma rays.

3.

State one harmful effect of ultraviolet radiation.

Skin damage or increased risk of skin cancer.

4.

State one harmful effect of X-rays or gamma rays.

Cell damage or increased risk of cancer.

5.

Explain why ionising radiation is more dangerous than visible light.

Ionising radiation has enough energy to remove electrons and damage cells.

6.

Explain why radiation dose affects the risk of harm.

A higher radiation dose increases the amount of ionising radiation absorbed and increases risk.

6.6.2.4 Uses and applications of electromagnetic waves

1.

Which electromagnetic wave is used for satellite communications?

Microwaves.

2.

Which electromagnetic wave is used in fibre optic communication?

Visible light.

3.

Which electromagnetic waves are commonly used for medical imaging and treatment?

X-rays and gamma rays.

4.

Explain why infrared radiation is suitable for thermal imaging cameras.

Infrared detects heat differences because warm objects emit more infrared radiation.

5.

Explain why microwaves are suitable for satellite communication.

Microwaves can travel through the atmosphere and carry information over long distances.

6.

Explain why X-rays are useful for medical imaging but must be used carefully.

X-rays pass through soft tissue but are absorbed by bones, allowing images to be produced. They must be controlled because they are ionising.

Topic 6 Review

1.

Compare transverse and longitudinal waves.

Transverse waves vibrate perpendicular to energy transfer. Longitudinal waves vibrate parallel to energy transfer.

2.

A wave has a speed of 340 m/s and a frequency of 170 Hz. Calculate its wavelength.

Wave equation:
v = fλ
340 = 170 × λ
λ = 2 m

3.

A wave has a period of 0.02 s. Calculate its frequency.

Frequency = 1 ÷ period
Frequency = 1 ÷ 0.02
Frequency = 50 Hz

4.

Explain why electromagnetic waves can travel through space but sound waves cannot.

Electromagnetic waves can travel through space because they do not need particles. Sound waves require particles to transfer vibrations.

5.

Compare the properties and hazards of ultraviolet, X-rays and gamma rays.

Ultraviolet, X-rays and gamma rays are ionising. UV can damage skin, X-rays can damage cells, and gamma rays have the highest penetration and can cause serious cell damage.

6.

Explain why different parts of the electromagnetic spectrum are suited to different applications.

Different electromagnetic waves have different wavelengths and frequencies, making them suitable for different uses such as communication, heating and medical imaging.

6.7.1.1 Poles of a magnet

1.

What happens when two north poles are brought close together?

Two north poles repel each other.

2.

What happens when a north pole and a south pole are brought close together?

A north pole and a south pole attract each other.

3.

What is meant by a non-contact force?

A non-contact force is a force that acts between objects without them touching.

4.

Explain the difference between a permanent magnet and an induced magnet.

A permanent magnet produces its own magnetic field. An induced magnet only becomes magnetic when placed in a magnetic field.

5.

Why does an induced magnet lose its magnetism when removed from a magnetic field?

An induced magnet loses its magnetism when removed from the magnetic field because its magnetic domains return to random arrangements.

6.

Explain why an induced magnet is always attracted to a permanent magnet.

An induced magnet is always attracted to a permanent magnet because the induced pole closest to the permanent magnet is always opposite.

6.7.1.2 Magnetic fields

1.

What is a magnetic field?

A magnetic field is the region around a magnet where magnetic forces act.

2.

Which materials are magnetic?

Magnetic materials include iron, steel, nickel and cobalt.

3.

Where is the magnetic field strongest around a bar magnet?

The magnetic field is strongest at the poles of a bar magnet.

4.

In which direction do magnetic field lines point?

Magnetic field lines point from the north pole to the south pole outside a magnet.

5.

Describe how you would use a plotting compass to map the magnetic field around a bar magnet.

Use a plotting compass to show the direction of the field at different points around the magnet, then join the points to draw field lines.

6.

Explain why a compass needle points north.

A compass needle points north because the Earth produces a magnetic field that interacts with the magnet in the compass.

6.7.2.1 Electromagnetism

1.

What happens around a wire when an electric current flows through it?

A magnetic field is produced around a wire when an electric current flows through it.

2.

Explain how increasing the current affects the magnetic field around a wire.

Increasing the current increases the strength of the magnetic field around the wire.

3.

Explain why a solenoid produces a stronger magnetic field than a straight wire.

A solenoid produces a stronger magnetic field because the magnetic fields from each loop of wire combine.

4.

Explain why adding an iron core increases the strength of an electromagnet.

Adding an iron core increases the strength of an electromagnet because iron becomes magnetised and strengthens the magnetic field.

5.

Draw and label the magnetic field pattern around a solenoid.

A solenoid has a magnetic field pattern similar to a bar magnet, with field lines passing through the centre of the coil and looping around the outside.

6.

Describe how you could demonstrate the magnetic field around a current-carrying wire.

Place a current-carrying wire near a plotting compass and observe the compass needle deflect. Increasing the current increases the deflection.

6.7.2.2 Fleming's left-hand rule (HT only)

1.

What is meant by the motor effect?

The motor effect is the force experienced by a current-carrying wire placed in a magnetic field.

2.

What does Fleming's left-hand rule predict?

Fleming's left-hand rule predicts the direction of the force on a current-carrying wire in a magnetic field.

3.

A wire carrying a current of 4 A is placed at right angles to a magnetic field of 0.5 T. If the wire is 0.30 m long, calculate the force acting on it.

Force = magnetic flux density × current × length
F = BIL
= 0.5 × 4 × 0.30
= 0.6 N

4.

A conductor 0.40 m long carries a current of 5 A and experiences a force of 2 N. Calculate the magnetic flux density.

Magnetic flux density = force ÷ (current × length)
B = 2 ÷ (5 × 0.40)
= 1 T

5.

State two factors that increase the force on a current-carrying wire in a magnetic field.

Increasing the current and increasing the magnetic field strength increase the force.

6.

Explain why there is no motor effect if the current is parallel to the magnetic field.

There is no motor effect when the current is parallel to the magnetic field because the wire does not cut through the magnetic field lines.

6.7.2.3 Electric motors (HT only)

1.

Explain why a current-carrying coil rotates in a magnetic field.

A current-carrying coil rotates in a magnetic field because the forces on opposite sides of the coil act in opposite directions, creating a turning force.

2.

What is the purpose of the split-ring commutator in a DC motor?

The split-ring commutator reverses the current in the coil every half turn so the coil continues rotating in the same direction.

3.

What is the function of the carbon brushes in an electric motor?

Carbon brushes transfer electrical current to the rotating coil.

4.

Explain why the current in the coil must reverse every half turn.

The current must reverse every half turn so the forces continue acting in the same direction and the coil keeps rotating.

5.

Describe the energy transfers that occur in an electric motor.

Electrical energy is transferred into kinetic energy, with some energy dissipated as thermal energy and sound.

6.

Explain how increasing the current or magnetic field strength affects the turning force on the motor.

Increasing the current or magnetic field strength increases the force on the coil, increasing the turning effect and making the motor rotate faster.

Topic 7 Review

1.

Compare permanent magnets and induced magnets.

Permanent magnets produce their own magnetic field. Induced magnets only become magnetic when placed in a magnetic field and lose their magnetism when removed.

2.

Explain how to plot the magnetic field around a bar magnet.

A magnetic field around a bar magnet can be plotted using a plotting compass. The compass is moved around the magnet and the direction of the field lines is recorded.

3.

Describe how a solenoid becomes an electromagnet.

A solenoid becomes an electromagnet when a current flows through the coil. Adding an iron core increases the magnetic field strength.

4.

A wire 0.25 m long carries a current of 8 A in a magnetic field of 0.6 T. Calculate the force acting on the wire.

Force = BIL
= 0.6 × 8 × 0.25
= 1.2 N

5.

Explain how Fleming's left-hand rule is used to predict the direction of the force on a current-carrying wire.

Fleming's left-hand rule shows the direction of the force by using the thumb for force, first finger for magnetic field direction and second finger for current direction.

6.

Explain how an electric motor converts electrical energy into kinetic energy.

An electric motor converts electrical energy into kinetic energy by using the motor effect to create a turning force on a current-carrying coil.

Physics

Paper 1

Topic 1 – Energy