Power and efficiency: OCR GCSE Physics A questions

Every OCR GCSE Physics A exam question on P7.2 Power and efficiency, 2018–2025, with its mark scheme and examiner’s report.

All 89 questions on Power and efficiency, as a list

June 2025, Paper 1 Foundation, Q21(a)(iii) (3 marks): The lift takes 1.2 minutes to move the passengers from the ground floor to the top floor. Calculate the power needed to move the maximum weight of passengers in
June 2025, Paper 2 Foundation, Q2 (1 mark): A hot drink is poured into a mug. Which method would not help to keep the drink hot? A Use a lid on the mug. B Use a mug with a larger surface area. C Use a mug
June 2025, Paper 2 Foundation, Q20(b)(i) (2 marks): The actual energy input to the games console in one hour is 5.2 × 105 J. Calculate the energy wasted by the games console in one hour of playing. Energy wasted
June 2025, Paper 2 Foundation, Q20(b)(ii) (2 marks): Explain why some energy is wasted when the student is playing on the games console. [2]
June 2025, Paper 2 Foundation, Q20(b)(iii) (3 marks): Calculate the efficiency of the game console. Use the equation: efficiency = useful output energy transfer input energy transfer Give your answer to 2 significa
June 2025, Paper 3 Higher, Q23(b)(i) (4 marks): Liquid B is placed in the freezer. The freezer needs 54 kJ of energy to cool liquid B from its initial temperature to its freezing point. This takes 360 s. Calc
June 2025, Paper 3 Higher, Q23(b)(ii) (1 mark): Why is the actual power needed to cool liquid B larger than your answer to (b)(i)? [1]
June 2025, Paper 4 Higher, Q19(c)(ii) (3 marks): When the fuel burns, 320 MJ of energy is wasted in one second. Calculate the efficiency of the rocket. Use the equation: efficiency = useful output energy trans
June 2024, Paper 1 Foundation, Q8 (1 mark): Person Q has a mass of 50 kg and climbs a vertical distance of 6 m in 6 s. Person R has a mass of 60 kg and climbs a vertical distance of 6 m in 5 s. Who has th
June 2024, Paper 1 Foundation, Q19(b)(ii) (3 marks): A different water rocket does 12 500 J of work in 5 seconds when it rises upwards. Calculate the power of this water rocket. Use the equation: power = work done
June 2024, Paper 2 Foundation, Q17(a) (1 mark): State the power of the filament lamp in kW. kW [1]
June 2024, Paper 2 Foundation, Q17(b) (2 marks): Calculate the energy transferred by the LED lamp during its lifetime. Use the equation: energy transferred = power × time Give your answer in kW h. Energy trans
June 2024, Paper 2 Foundation, Q17(c) (1 mark): In 1 year, the filament lamp transfers 110 kW h of energy. This costs £22.00. What is the cost of 1 kW h of electricity? Cost = £ [1]
June 2024, Paper 2 Foundation, Q17(d) (1 mark): Calculate the number of filament lamps a person must buy during the lifetime of one LED lamp. Number of filament lamps = [1]
June 2024, Paper 2 Foundation, Q17(e) (2 marks): Suggest one reason for and one reason against using LED lamps. Use the data in the table. For Against [2]
June 2024, Paper 2 Foundation, Q17(f) (3 marks): One LED lamp has an efficiency of 0.4. In one second, the input energy transferred by the lamp is 10 J. Calculate the energy wasted by the lamp in one second. u
June 2024, Paper 2 Foundation, Q17(g)(i) (1 mark): A person buys an LED lamp. After how many days is the total cost of the LED lamp the same as the total cost of the filament lamp? Use the graph. Number of days
June 2024, Paper 2 Foundation, Q17(g)(ii) (2 marks): The person uses the LED lamp for 100 days. How much money does the person save by buying and using the LED lamp instead of the filament lamp? Use the graph. Mon
June 2024, Paper 4 Higher, Q13 (1 mark): In one month a wind turbine on a house generates 300 kW h of useful energy. The efficiency of the wind turbine is 0.60. What is the wasted energy in one month?
June 2023, Paper 2 Foundation, Q17(a) (6 marks): Corrugated cardboard can be used as an insulator around a beaker. Student A does an experiment to investigate how the thickness of corrugated cardboard wrapped
June 2023, Paper 2 Foundation, Q17(b)(i) (1 mark): Describe the trend shown by the students’ results. [1]
June 2023, Paper 2 Foundation, Q17(b)(ii) (1 mark): Describe how the table shows the students’ results are reproducible. [1]
June 2023, Paper 2 Foundation, Q17(b)(iii) (2 marks): The student plots a graph of temperature against time. Temperature Time State two reasons why the graph does not show that the temperature is directly proportio
June 2023, Paper 2 Foundation, Q20(d) (2 marks): The test is repeated with a different car. The potential energy of this car at the top of the hill is 120 000 J. The kinetic energy of this car at the bottom of
June 2023, Paper 3 Higher, Q23(a)(ii) (3 marks): It takes 5 minutes for the freezer to cool the vaccines. Calculate the power of the freezer. Use the Equation Sheet. Power = W [3]
June 2023, Paper 3 Higher, Q23(a)(iii) (2 marks): Suggest two reasons why the actual power of the freezer will be greater than that calculated in part (a)(ii). 1 2 [2]
June 2023, Paper 4 Higher, Q12 (1 mark): A coal fired power station has an efficiency of 0.4. What is the input energy needed to obtain a useful output energy of 500 MJ? useful output energy transfer U
June 2022, Paper 2 Foundation, Q11 (1 mark): A lamp has an input energy of 200 J. The useful output energy is 80 J. What is the efficiency of the lamp? Use the Data Sheet. A 0.4 B 2.5 C 40 D 250 Your answe
June 2022, Paper 2 Foundation, Q14 (1 mark): Which row describes the walls of a building with the lowest rate of cooling? Thickness Thermal conductivity of walls of walls A thick high B thick low C thin hi
June 2022, Paper 4 Higher, Q1 (1 mark): Which row describes the walls of a building with the lowest rate of cooling? Thickness Thermal conductivity of walls of walls A thick high B thick low C thin hi
June 2022, Paper 4 Higher, Q3 (1 mark): Power can be measured in watts (W) or milliwatts (mW). What is 1.5 mW converted into W? 1.5 × 10–6 W A 1.5 × 10–3 W B 1.5 × 103 W C 1.5 × 106 W D Your answer [1
June 2022, Paper 4 Higher, Q13 (1 mark): Room Y and Room Z are identical rooms. No energy can escape from the rooms. The temperature of each room is increased by using a different heater. Room Y Room Z
June 2022, Paper 4 Higher, Q21(a)(ii) (5 marks): The wind turbine has an efficiency of 0.35. Calculate the input energy per second when the wind speed is 10 m / s. Use Fig. 21.1 and the Data Sheet. Give your a
November 2021, Paper 1 Foundation, Q22(a)(ii) (3 marks): The power of the lift is 50 W. Calculate the time taken for the lift to move these boxes from ground to lorry level. Use the equation: power = work done / time
November 2021, Paper 2 Foundation, Q10 (1 mark): A 3.0 kW oven is switched on for 1.5 hours. Calculate the energy transferred by the oven. Use the equation: energy transferred = power × time A 2.0 J B 2.0 kWh
November 2021, Paper 2 Foundation, Q17(b)(i) (2 marks): Calculate the efficiency of the motor. Use the equation: efficiency = useful output energy transfer / input energy transfer Efficiency = [2]
November 2021, Paper 2 Foundation, Q17(b)(ii) (2 marks): Explain why the efficiency of the motor is not 100%. [2]
November 2021, Paper 2 Foundation, Q17(b)(iii) (2 marks): The crane’s lifting equipment contains moving parts. A workman suggests adding oil to these moving parts. Explain how this will affect the efficiency. [2]
November 2021, Paper 2 Foundation, Q20(a) (1 mark): Each kettle has the same efficiency and is used for the same time. Describe one other factor the students should control in their method. [1]
November 2021, Paper 2 Foundation, Q20(b) (6 marks): A group of students compare the power of three kettles A, B and C using this method: • They pour water in each kettle. • They plug the kettles in and switch the
November 2021, Paper 3 Higher, Q22(b) (3 marks): The work done by the athlete after completing one lap of the track is 3000 J. It takes the athlete 60 s to complete one lap. Calculate the power of the athlete.
November 2021, Paper 4 Higher, Q5 (1 mark): How can unwanted energy transfer be reduced? A By adding lubrication B By decreasing efficiency C By increasing friction D By removing thermal insulation Your a
November 2021, Paper 4 Higher, Q20(a) (3 marks): Use the data in Table 20.1 to calculate the efficiency of the heater. Efficiency = [3]
November 2021, Paper 4 Higher, Q20(b) (3 marks): The heater is used for 5 minutes. Calculate the power of the heater. Use the data in Table 20.1 and the equation: energy transferred = power × time Power = W [3
November 2020, Paper 1 Foundation, Q19(c)(ii) (3 marks): Calculate the power output of this toy car if the work is done over 75 seconds. Use your answer from (c)(i). Power = W [3]
November 2020, Paper 2 Foundation, Q1 (1 mark): A motor has an input energy of 800 J. The useful output energy is 500 J. What is the wasted energy? A 300 J B 500 J C 800 J D 1300 J Your answer [1]
November 2020, Paper 2 Foundation, Q3 (1 mark): A radiator has a power of 2 kilowatts (2 kW). Convert 2 kW into watts. A 0.002 W B 200 W C 2000 W D 2 000 000 W Your answer [1]
November 2020, Paper 2 Foundation, Q22(a) (3 marks): Describe a method she can use to do this investigation. [3]
November 2020, Paper 2 Foundation, Q22(b)(i) (2 marks): Plot the results on the grid in Fig. 22.1. Two of the points have been plotted for you. [2]
November 2020, Paper 2 Foundation, Q22(b)(ii) (1 mark): Draw a line of best fit on your graph. [1] 100 80 60 Temperature of water (°C) 40 20 0 0 2 4 6 8 10 12 Time (minutes) Fig. 22.1
November 2020, Paper 2 Foundation, Q22(b)(iii) (2 marks): Describe how the temperature of the water changes with time. Use data from the graph in Fig. 22.1 in your answer. [2]
November 2020, Paper 2 Foundation, Q22(b)(iv) (1 mark): The thickness of the cardboard box is doubled. Everything else stays the same. Sketch a line on the graph in Fig. 22.1 to suggest what these new results may loo
November 2020, Paper 2 Foundation, Q22(b)(v) (1 mark): Suggest one way to improve the investigation. [1]
November 2020, Paper 2 Foundation, Q22(c) (1 mark): Explain why the rate of cooling of a metal box is different to a cardboard box. Assume the thickness of the walls is the same in both boxes. [1]
November 2020, Paper 3 Higher, Q2 (1 mark): A student uses 2250 J of energy climbing up steps. It takes the student 15 seconds to climb the steps. Calculate the power of the student. Use the equation: pow
November 2020, Paper 3 Higher, Q13 (1 mark): A student is measuring power of different machines. Which two measurements show the same power measured? 10 GW and 1.0 × 1010 W A 4.0 kW and 40 × 103 W B 10 mW
November 2020, Paper 4 Higher, Q17(a) (3 marks): Describe a method she can use to do this investigation. [3]
November 2020, Paper 4 Higher, Q17(b)(i) (2 marks): Plot the results on the grid in Fig. 17.1. Two of the points have been plotted for you. [2]
November 2020, Paper 4 Higher, Q17(b)(ii) (1 mark): Draw a line of best fit on your graph. [1] 100 80 60 Temperature of water (°C) 40 20 0 0 2 4 6 8 10 12 Time (minutes) Fig. 17.1
November 2020, Paper 4 Higher, Q17(b)(iii) (2 marks): Describe how the temperature of the water changes with time. Use data from the graph Fig. 17.1 in your answer. [2]
November 2020, Paper 4 Higher, Q17(b)(iv) (1 mark): The thickness of the cardboard box is doubled. Everything else stays the same. Sketch a line on the graph in Fig. 17.1 to suggest what these new results may loo
November 2020, Paper 4 Higher, Q17(b)(v) (1 mark): Suggest one way to improve the investigation. [1]
November 2020, Paper 4 Higher, Q17(c) (1 mark): Explain why the rate of cooling of a metal box is different to a cardboard box. Assume the thickness of the walls is the same in both boxes. [1]
November 2020, Paper 4 Higher, Q21(b)(i) (5 marks): Table 21.1 gives some information about a different kettle. Energy transferred to the kettle 525 000 J Mass of water 1.2 kg Starting temperature of water 25 °C
November 2020, Paper 4 Higher, Q21(b)(ii) (1 mark): Explain why the efficiency of the kettle is less than 100%. [1]
June 2019, Paper 1 Foundation, Q19(a)(i) (1 mark): Lift C takes 12 s to move between the two floors. Draw a bar for lift C on the bar chart. [1]
June 2019, Paper 1 Foundation, Q19(a)(ii) (2 marks): Calculate the mean time of the three lift journeys. Mean = s [2]
June 2019, Paper 1 Foundation, Q19(a)(iii) (2 marks): Explain which lift uses the most power. [2]
June 2019, Paper 1 Foundation, Q19(b)(i) (4 marks): One lift uses 50 000 J for a 12 s journey. Calculate the power of the lift. Give your answer to 1 decimal place. Power = W [4]
June 2019, Paper 2 Foundation, Q5 (1 mark): A boiler has an input energy of 720 kJ from the gas it burns. It transfers 540 kJ of useful energy to the home. What is the efficiency of the boiler? Use the eq
June 2019, Paper 2 Foundation, Q16(a)(i) (1 mark): Calculate the temperature difference when the thickness of insulation is 12 mm. Temperature difference = °C [1]
June 2019, Paper 2 Foundation, Q16(a)(ii) (1 mark): The result when the thickness of the insulation is 12 mm is anomalous. Suggest a reason why this result appears to be anomalous. [1]
June 2019, Paper 2 Foundation, Q16(b) (2 marks): Plot a graph of the results in Table 16.1 and draw a line of best fit. Ignore the anomalous result for 12 mm. 30 25 20 Temperature 15 difference (°C) 10 5 0 0 2
June 2019, Paper 2 Foundation, Q16(c) (1 mark): Describe how the temperature difference is affected as the thickness of the insulation increases. [1]
June 2019, Paper 2 Foundation, Q16(d) (1 mark): Suggest how the thickness of the insulation affects the rate of cooling of the tea. [1]
June 2019, Paper 2 Foundation, Q16(e) (2 marks): This experiment could be improved. Describe two different ways of improving the experiment. 1 2 [2]
June 2019, Paper 2 Foundation, Q24(a) (3 marks): A TV has a power rating of 0.2 kW. Calculate the energy transferred, in kWh, if the TV is switched on for 4 hours. Energy transferred = kWh [3]
June 2019, Paper 4 Higher, Q14 (1 mark): A boiler has an input power of 12 kW from the gas it burns. Its efficiency is 0.75. Which row in the table shows the correct values for this boiler? Useful outp
June 2019, Paper 4 Higher, Q16(a) (3 marks): A TV has a power rating of 0.2 kW. Calculate the energy transferred, in kWh, if the TV is switched on for 4 hours. Energy transferred = kWh [3]
June 2018, Paper 1 Foundation, Q16(a)(i) (1 mark): Which appliance uses the most energy? [1]
June 2018, Paper 1 Foundation, Q16(a)(ii) (1 mark): Which appliance uses the least energy? [1]
June 2018, Paper 2 Foundation, Q8 (1 mark): A vehicle has an input power from fuel of 20 kW and a useful output power of 6 kW. Calculate the power it wastes. A 3 kW B 6 kW C 14 kW D 20 kW Your answer [1]
June 2018, Paper 2 Foundation, Q18(a)(i) (2 marks): Calculate the energy input per hour in J for electric motor D. Answer = J [2]
June 2018, Paper 2 Foundation, Q18(a)(ii) (1 mark): Which electric motor has the lowest ‘wasted’ energy in one hour? [1]
June 2018, Paper 2 Foundation, Q18(a)(iii) (1 mark): Which electric motor has the highest ‘wasted’ energy in one hour? [1]
June 2018, Paper 2 Foundation, Q18(a)(iv) (1 mark): Describe how energy is ‘wasted’ in an electric motor. [1]
June 2018, Paper 2 Foundation, Q18(a)(v) (1 mark): Suggest how this ‘wasted’ energy can be reduced in an electric motor. [1]
June 2018, Paper 2 Foundation, Q18(b) (3 marks): Calculate the % efficiency of electric motor E. Use the equation: Efficiency = Useful output energy transfer / Input energy transfer Give your answer to 2 signi
June 2018, Paper 4 Higher, Q10 (1 mark): A gas fire, used to heat a room, has an input energy transfer of 180 000 J per minute. The fire has an efficiency of 0.8. Use the equation: Efficiency = Useful

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