Electricity (AQA GCSE Combined Science: Synergy: Physical Sciences): Exam Questions

Two students investigated how the current in filament lamp L varied with the potential difference across the lamp.

Figure 9 shows the circuit used.

What is component P?

The resistance of the variable resistor is increased.

How does increasing the resistance of the variable resistor affect the reading on the ammeter?

Figure 10 shows the results.

Figure 11 shows the line of best fit drawn by each student.

Explain why student B's line of best fit is correct.

What type of error will have caused the point at 2 V to be above the line of best fit?

When the potential difference across the filament lamp is 1.5 V, the current in the lamp is 0.3 A.

Calculate the resistance of the filament lamp.

Use the equation:

$\text{resistance}=\frac{\text{potential difference}}{\text{current}}$

The students investigated how the length of a wire affects the resistance of the wire.

Figure 12 shows the circuit used.

The temperature of the wire was kept constant.

Identify the variables in the investigation.

Tick one box in each row.

Figure 15 shows how the National Grid connects a power station to houses.

The National Grid transfers electrical power efficiently from power stations to houses.

The step-down transformer supplies mains electricity to the houses.

Complete the sentence.

Choose the answer from the box.

The step-down transformer decreases the -------------.

Figure 16 shows an electric kettle plugged into a socket in a house.

The cable connecting the kettle to the socket is a three-core cable.

The insulation on each wire is a different colour.

Draw one line from each wire to the colour of insulation.

Use the Physics Equations Sheet to answer this question.

Which equation links charge flow (Q), energy (E) and potential difference (V)?

Use the Physics Equations Sheet to answer this question.

The kettle is switched on to heat some water.

The energy transferred to the heating element in the kettle is 260 000 J.

The potential difference across the heating element is 1.3 V.

Calculate the charge flow in the heating element.

Figure 17 shows a desk lamp connected to the mains electricity supply.

The desk lamp is fitted with a high-efficiency LED bulb.

What does ‘high-efficiency’ mean?

The output power of the lamp is 2.8 W.

Calculate the energy transferred by the lamp in 60 seconds.

Use the equation:

$\text{energy transferred}=\text{power}\times \text{time}$

Mains electricity can be dangerous.

Table 2 shows information about the effects of different electrical supplies on the human body.

Table 2

ac is alternating current.

Compare the effects on the human body of 50 Hz ac with 10 000 Hz ac.

Use data from Table 2.

A normal bicycle can be converted into an electric bicycle.

Figure 9 shows a converted bicycle.

Figure 9

Figure 10 shows the circuit diagram for the bicycle.

The switch is used to turn the motor on or off.

Explain how the variable resistor is used to control the speed of the motor.

The battery can be recharged using the mains electricity supply.

The mains supply is alternating current.

Figure 11 shows a simplified version of the circuit that is used to recharge the battery.

Figure 11

Explain why charge only passes in one direction through the circuit.

The mains supply fully recharged the battery in 2 hours.

The mean charging current was 5.0 A.

The resistance of the battery was 0.18 Ω.

Calculate the energy dissipated due to the resistance of the battery in 2 hours.

Use the Physics Equations Sheet.

A student carried out an investigation using an electrical circuit.

Figure 8 shows the circuit used.

Figure 8

The student increased the resistance of the variable resistor.

Describe what happened to the potential difference across resistor R and the current in resistor R.

The student investigated how the current in resistor R varied with the potential difference across resistor R.

To keep the temperature of resistor R constant, the student opened the switch after taking each reading.

Figure 9 shows the results.

Figure 9

Explain what happens to the resistance of resistor R as the potential difference across resistor R increases.

Use information from Figure 9.

After the reading was taken at 4.0 V, the student did not open the switch before taking the reading at 5.0 V.

Explain why the current was lower than expected when the 5.0 V reading was taken.

The student had more resistors with the same resistance as resistor R.

Describe a method to investigate how the number of resistors in parallel affects the total resistance of the resistors in parallel.

Figure 10 shows a step-down transformer that is part of a circuit inside a computer.

The transformer connects the mains supply to the computer circuit.

Figure 10

The potential difference across the primary coil is 230 V.

The potential difference across the secondary coil is 48.0 V.

The current in the primary coil is 2.40 A.

Calculate the current in the secondary coil.

Use the Physics Equations Sheet.

The current in the primary coil is 2.40 A.

Calculate the time taken for a charge of 288 C to flow past a point in the primary coil.

Use the Physics Equations Sheet.

Give your answer in minutes.

Figure 11 shows the mains electricity circuit for the transformer.

Figure 11

An electrician replaced a faulty switch connecting the transformer to the mains supply.

The circuit was disconnected from the mains supply to prevent the electrician from receiving an electric shock.

Explain why the electrician could have received a shock if the circuit was connected.

Table 2 shows information about the effects of different electrical supplies on the human body.

Table 2

ac is alternating current.

dc is direct current.

The mains electricity supply in the UK is ac with a frequency of 50 Hz.

Describe why it would be better if the UK mains supply was not 50 Hz ac.

A student investigated resistance in a circuit. The student measured:

• the current in the resistor with an ammeter

• the potential difference across the resistor with a voltmeter

Figure 3 shows a circuit diagram.

Which letter on Figure 3 shows the correct position for the ammeter to measure the current in the resistor?

Tick (✓) one box.

Draw the circuit symbol for a voltmeter in the box .

The student changed the number of identical resistors in the circuit.

The student calculated the total resistance of the resistors.

Figure 4 shows the results.

Draw a line of best fit on Figure 4.

Predict the total resistance when 5 resistors were connected in the circuit.

You should extend your line of best fit.

Total resistance = _____________ Ω

How were the identical resistors connected in the student’s circuit?

Use Figure 4.

Tick (✓) one box.

The potential difference across the battery was 3.0 V.

The maximum current in the circuit in the student’s investigation was 0.25 A.

Calculate the maximum power output of the battery in the student’s investigation.

Use the equation:

$\text{power}=\text{potential difference}\times \text{current}$

Power = W

FIGURE 1 shows how the National Grid connects a nuclear power station to houses.

Figure 1

What is ONE advantage of generating electricity using nuclear power?

The step-up transformer INCREASES the efficiency of power transmission.

How does the step-up transformer affect the potential difference across the transmission cables?

How does the step-up transformer affect the current in the transmission cables?

How does the step-up transformer affect the energy transferred from the transmission cables to the surroundings?

The total power input from the nuclear power station to the National Grid is 2400 MW.

efficiency of power transmission = 0.90

Calculate the useful power output in MW.

Use the equation:

$\text{useful power output}=\text{efficiency}\times \text{total power input}$

TABLE 1 shows the percentage (%) of electricity generated by all the energy resources in the UK on one day in 2022.

TABLE 1

Calculate percentage X in TABLE 1.

FIGURE 8 shows how the potential difference of the mains electricity supply varies with time.

FIGURE 8

How does FIGURE 8 show that the potential difference is alternating?

What is the potential difference of the mains electricity supply in the UK?

FIGURE 9 shows a student using hair straighteners connected to the mains electricity supply by a three-core cable.

The hair straighteners are connected to the mains electricity supply by a three-core cable.

Draw ONE line from the name of each wire to the function of each wire in the cable.

FIGURE 10 shows the circuit diagram for the hair straighteners.

FIGURE 10

The resistors A, B, C and D represent four heating elements in the hair straighteners.

Complete TABLE 3 to show how switches S1 and S2 are used to switch the heating elements on or off.

The first row of the table has been completed for you.

Use the Physics Equations Sheet to answer this question.

Write down the equation which links energy transferred (E), power (P) and time (t).

When the hair straighteners are switched off, the heating elements take 20 minutes to cool to room temperature.

The mean power transfer to the surroundings during this time is 12 W.

Calculate the energy transferred to the surroundings by the heating elements in 20 minutes.

A solar cell generates a potential difference when light shines on its surface.

A student investigated how the potential difference varied with the light intensity at the surface of the solar cell.

Figure 13 shows some of the equipment used by the student.

The voltmeter displayed the potential difference generated by the solar cell.

The student varied the light intensity by changing the height of the torch above the solar cell.

Figure 14 shows the results.

Describe a method the student could have used to obtain the results shown in Figure 14.

The circuit symbol for a solar cell is

Figure 15 shows the solar cell in a circuit with an LED and a resistor.

Figure 16 shows how the current in the LED varies with the potential difference across the LED.

What is the range of potential difference values for which the LED emits light in Figure 16?

Range of values =_____________ to __________ V

Use the Physics Equations Sheet to answer questions 09.3 and 09.4.

Which equation links current ($I$), potential difference ($V$) and resistance ($R$)?

Tick (✓) one box.

Determine the resistance of the LED when the potential difference across the LED is 2.7 V.

Use Figure 16.

Resistance = _____________ Ω

Describe how the resistance of the LED varies as the p.d. increases from 0 V to 3.7 V.

Use data from Figure 16.

Figure 17 shows two different designs of wind turbine.

To generate electricity, the three-blade wind turbine rotates about an axis.

To generate electricity, the bladeless wind turbine oscillates from side to side.

Table 6 gives information about the two designs.

Table 6

Which feature of the three-blade turbine is an advantage compared with the bladeless turbine?

Use Table 6.

Give a reason for your answer.

Feature ___________________________________________________

Reason ___________________________________________________

To generate electricity, the bladeless wind turbine oscillates from side to side.

Figure 18 shows the direction of the oscillations of the bladeless wind turbine.

Figure 19 shows how the power output of the bladeless turbine varies with the frequency of the oscillation.

Describe how the power output of the bladeless turbine varies with frequency.

The energy from wind turbines can be used to recharge a battery.

Use the Physics Equations Sheet to answer questions 10.3 and 10.4.

Which equation links charge flow ($Q$), current ($I$) and time ($t$)?

Tick (✓) one box.

To fully recharge the battery, a charge of 216 000 C needs to flow through the battery.

The current in the battery is 5.0 A.

Calculate the time taken to fully recharge the battery.

Give the unit.

Time taken = _____________Unit _____________

FIGURE 7 shows how the potential difference of the mains electricity supply varies with time.

How does FIGURE 7 show that the potential difference is alternating? [1 mark]

What is the potential difference of the mains electricity supply in the UK? [1 mark]

Mains potential difference =________________ V

What is the frequency of the mains electricity supply in the UK? [1 mark]

Mains frequency = _____________________ Hz

FIGURE 8 shows a student using hair straighteners.

The hair straighteners contain heating elements which transfer thermal energy to the hair.

The hair straighteners are connected to the mains electricity supply by a three-core cable.

What is the function of the earth wire in the three-core cable?

Tick (✓) ONE box. [1 mark]

FIGURE 9 shows the circuit diagram for the hair straighteners.

The resistors A, B, C and D represent four identical heating elements in the hair straighteners.

The hair straighteners have two power settings.

Describe how using S₁ and S₂ controls the power output of the hair straighteners. [3 marks]

When the hair straighteners are switched off, the heating elements cool down to room temperature.

The energy transferred to the surroundings is 14.4 kJ.

The mean power transfer to the surroundings is 12 W.

Calculate the time taken for the heating elements to reach room temperature.

Use the Physics Equations Sheet. [4 marks]

Time = ________________________ s

A hairdryer contains a heating element and a motor.

The motor is connected to a fan.

The symbol for the heating element is shown below.

The symbol for the motor is M is shown below.

Figure 2 shows part of the electrical circuit inside the hairdryer.

How does the current in the motor compare with the current in the heating element?

Give a reason for your answer.

Tick (✓) one box.

The potential difference across the motor is 20 V.

What is the potential difference across the heating element?

Give a reason for your answer.

Tick (✓) one box.

The hairdryer transfers 460 000 J of energy in 250 seconds.

Calculate the power of the hairdryer.

Use the equation:

power = energy transferred / time

The current in the hairdryer is 8.0 A.

Calculate the time taken for 1200 C of charge to flow past a point in the hairdryer circuit.

Use the equation:

$time=\frac{chargeflow}{current}$

The hairdryer is connected to the mains electricity supply.

What is the frequency of the UK mains electricity supply?

Tick (✓) one box.

The power output of the generator in the wind turbine is 144 000 W.

The potential difference across the generator is 960 V.

Calculate the current in the generator.

Current = _______________________ A

Use the Physics Equations Sheet.

A student investigated how the current in a filament lamp varies with the potential difference across the filament lamp.

Figure 11 shows the circuit used.

What is component P?

Tick (✓) one box.

The student measured different values of potential difference and the corresponding values of current for the filament lamp.

Describe how the student could use the circuit in Figure 11 to make these measurements.

Figure 12 shows the reading on the ammeter at one point in the investigation.

What is the reading on the ammeter?

Ammeter reading = _______________ A

The student repeated the investigation for two other components.

The student plotted a graph of current against potential difference for each component.

Draw one line from each component to the correct graph.

A student investigated how the resistance of a wire varies with the length of the wire.

Figure 6 shows how the student connected the wire to a circuit.

Figure 6: A length of wire stretched between two crocodile clips that are connected to the rest of the circuit.

Which piece of equipment should the student use to measure the length of wire between the crocodile clips?

The student used readings from the circuit to calculate the resistance of the wire at different lengths.

Figure 7 shows the results.

Figure 7: Resistance (Ω) on the y-axis (0 to 25) and Length of wire (cm) on the x-axis (0 to 100). The data points lie approximately on a straight line through the origin.

Draw a line of best fit on Figure 7.

A 100 cm length of wire is placed between the crocodile clips.

Predict the resistance of the 100 cm length of wire.

Use Figure 7.

Describe how the results on Figure 7 show that resistance is directly proportional to length.

The student switched the circuit off between readings.

Another student did the same investigation but did not switch the circuit off between readings.

What would happen to the temperature of the wire if the circuit was not switched off between readings?

What would happen to the resistance of the wire if the circuit was not switched off between the readings?

When the student switched the circuit off the ammeter reading was 0.02 A.

What type of error caused the ammeter reading to be 0.02 A?

Tick (✓) one box.

Figure 3 shows how the National Grid links a nuclear power station to consumers.

Figure 3

Explain why step-up transformers are used in the National Grid.

Explain why step-down transformers are used in the National Grid.

Figure 4 shows a transformer.

Figure 4

The potential difference across the primary coil is 345 kV.

The potential difference across the secondary coil is 230 V.

The current in the primary coil is 0.060 A.

Calculate the current in the secondary coil.

Use the Physics Equations Sheet.

A cordless hairdryer contains a heating element and a fan.

The hairdryer is powered by a rechargeable battery.

Figure 10 shows the cordless hairdryer.

Figure 10

The power output of the heating element is 0.24 kW when the potential difference across the heating element is 16 V.

Calculate the current in the heating element.

Use the Physics Equations Sheet.

The battery of the hairdryer can be recharged from 0 to 100% in 6.0 hours.

The power input to the battery is 18 W.

The potential difference across the battery is 24 V.

Calculate the charge flow through the battery in 6.0 hours.

Use the Physics Equations Sheet.

A thermistor is an electrical component.

What is the circuit symbol for a thermistor?

Tick (✓) one box.

A student investigated how the resistance of a thermistor varies with temperature.

Figure 7 shows the results.

Figure 7

Suggest why the student was not able to take measurements at temperatures below 20 °C.

The student used an ammeter and a voltmeter to take measurements to determine the resistance of the thermistor.

Describe a method the student could have used to obtain the results shown in Figure 7.

Use the Physics Equations Sheet to answer this question.

Write down the equation which links current (I), potential difference (V) and resistance (R).

The potential difference across the thermistor was 6.0 V.

Determine the current in the thermistor when the temperature of the thermistor was 40 °C.

Use Figure 7.

A student investigated electrical circuits.

Figure 13 shows a circuit the student made.

Figure 13

The student increased the resistance of the variable resistor from 0 to 15 Ω.

Explain what happened to the readings on the voltmeter and ammeter as the resistance was increased.

The student changed the position of the voltmeter.

Figure 14 shows the new circuit.

Figure 14

The student connected the voltmeter across the 15 Ω fixed resistor.

The student used the variable resistor to vary the potential difference across the fixed resistor.

The potential difference across the fixed resistor can only be varied between 6 V and 12 V using the circuit in Figure 14.

Explain why.

Give one way the student could vary the potential difference across the fixed resistor below 6 V.

We use mains electricity in our homes.

What is the frequency of the UK mains electricity supply?

Tick (✓) one box.

Many appliances in the home use three-core electrical cable.

Figure 7

Label the wires in the cable in Figure 7.

Use words from the box.

Box: Earth, Negative, Neutral, Positive

The sentences explain how touching the live wire in a cable can cause an electric shock.

Complete the sentences. Use words from the box.

Box: current, force, resistance, potential difference

Touching the live wire causes a large to exist across the body.

This causes a through the body, which results in an electric shock.

A heater has a power rating of 2500 W.

The heater is turned on for 180 seconds.

Calculate the energy transferred by the heater.

Use the equation:

$\text{energy transferred}=\text{power}\times \text{time}$

Give your answer in kilojoules (kJ).

Energy transferred = kJ

Write down the equation that links charge flow, energy transferred and potential difference.

The mains electricity supply is at 230 V.

A different heater transfers 4200 J of energy.

Calculate the charge flow through the heater.

Charge flow = C

In an electrolysis cell the current is 1.5 × 10⁵ A, at a potential difference of 4 V.

Calculate the energy transferred by the electrolysis cell in 24 hours.

Energy transferred = J

An electric current is a flow of electrical charge through a circuit.

Complete the sentence. Use a word from the box.

Metals are good conductors of electricity because electrical charge is transferred by delocalised ---------------------.

Draw one line from each symbol to the name of the component.

Table 2 shows information about some electrical appliances.

Table 2

A student plugs all four of the appliances into one multi-way socket.

The mains electricity is 230 V.

The highest safe current in the socket is 30 A.

Explain why it is not safe to use all four appliances at the same time.

In your answer you should:

• calculate the total power needed

• use the equation

$\text{current}=\frac{\text{power}}{\text{potential difference}}$

to calculate the total current needed.

Figure 8 shows how electrical power is transferred from power stations to consumers using the National Grid.

Figure 8

Transformer 1 is a step-up transformer.

Explain why step-up transformers are used in the National Grid.

What is the purpose of Transformer 2?

A student is investigating some electrical components.

Describe how the student could set up a circuit to find the resistance of a lamp.

You should include a circuit diagram in your answer.

The student is given an electrical component in a sealed box.

She has to find out what the electrical component is by experiment.

The student records the current and the potential difference for the component.

Her results are shown in Figure 6 .

Figure 6

Explain how the student could know that the electrical component in the sealed box is not an ohmic conductor.

What is the electrical component in the sealed box?

Explain your answer.

Component:

Explanation:

Use the graph (Figure 6) to determine the resistance of the component at 2.3 V.

Resistance = Ω

A student used electrical circuits to investigate the relationship between resistance, potential difference and current.

Figure 8 shows how the student connects the first circuit he set up.

Figure 8

The circuit does not work.

Draw the correct circuit.

The student then sets up the circuit correctly.

Look at Figure 9.

Figure 9

What is the reading on the voltmeter?

The student then set up a circuit to investigate how resistance affects the brightness of a lamp.

Figure 10 shows the circuit he set up.

Figure 10

The student increases the resistance of the variable resistor.

What effect does this have on the brightness of the lamp?

Explain your answer.

Write down the equation that links current, potential difference and resistance.

When the potential difference across the lamp is 3.3 V the current is 0.15 A.

Calculate the resistance of the lamp in the student's experiment.

Resistance = Ω