Lesson 4.1.2.2

4.1.2.2 Efficiency Quiz: AQA Physics, Unit 1

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 4.1.2.2, Efficiency: 20 multiple choice questions for the AQA GCSE Physics (8463), Unit 1: Energy, written with Revision Ninja.

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The 20 questions

  1. What is the correct numerator for calculating energy efficiency?

    • Wasted output energy
    • Total input energy
    • Maximum potential energy
    • Useful output energy

  2. Efficiency can also be calculated using useful power output and what else?

    • Wasted power input
    • Useful power input
    • Total power input
    • Total power output

  3. An efficiency of 0.75 is equivalent to what percentage?

    • 7.5%
    • 75%
    • 0.75%
    • 750%

  4. A motor takes in 500 J and usefully transfers 400 J. What is its efficiency?

    • 0.2
    • 0.8
    • 80
    • 1.25

  5. A heater has a total power input of 2000 W and a useful power output of 1500 W. What is its efficiency as a percentage?

    • 133%
    • 75%
    • 3500%
    • 25%

  6. A lamp has an efficiency of 10%. What percentage of its input energy is wasted?

    • 90%
    • 50%
    • 10%
    • 100%

  7. A machine has an efficiency of 0.6 and total input energy of 5000 J. What is the useful energy output?

    • 5600 J
    • 8333 J
    • 2000 J
    • 3000 J

  8. A pump has useful output 240 W and efficiency 0.8. What is the total power input?

    • 192 W
    • 300 W
    • 320 W
    • 240 W

  9. What is the maximum possible numerical value of efficiency for real machines?

    • Zero
    • Less than one
    • Always exactly two
    • Greater than one

  10. What is the efficiency and wasted energy for a 60 J useful and 200 J input device?

    • 3.0 and 200 J
    • 0.3 and 60 J
    • 0.6 and 140 J
    • 0.3 and 140 J

  11. Which device is more efficient for giving the same light output?

    • Filament lamp
    • Incandescent bulb
    • LED lamp
    • Halogen bulb

  12. A motor wastes 1200 J of energy for every 3000 J input. What is its efficiency?

    • 0.4
    • 2.5
    • 0.2
    • 0.6

  13. A 2000 W device is 25% efficient. What useful power output does it give?

    • 8000 W
    • 1500 W
    • 500 W
    • 250 W

  14. What percentage of energy is wasted by a device with efficiency 0.45?

    • 45%
    • 0.55%
    • 55%
    • 145%

  15. Which change increases the efficiency of an electric room heater?

    • Painting walls dark
    • Adding wall insulation
    • Increasing input voltage
    • Removing insulation

  16. What change improves the efficiency of a moving mechanical bearing?

    • Rougher surfaces
    • Removing lubricant
    • Increasing load
    • Adding lubricant

  17. A motor's efficiency is 0.85 and its useful output is 340 J. What is its total energy input?

    • 400 J
    • 425 J
    • 289 J
    • 340 J

  18. A machine has efficiency 60%. If its input energy doubles while useful output stays the same, what is the new efficiency?

    • 60%
    • 15%
    • 120%
    • 30%

  19. Why is a practical measured efficiency often lower than expected?

    • Zero resistance
    • Energy created
    • Energy wasted
    • Conservation violated

  20. A device has a total power input of 500 W and an efficiency of 0.9. How much power is wasted?

    • 5 W
    • 50 W
    • 450 W
    • 550 W

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