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Efficiency

9th grade (Year 10 in England) · 16 questions · Common Core: NGSS.HS-PS3-3 · England: KS4 Combined Science: Energy

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  1. Question 1

    How can a house be made more energy efficient?

    • A. remove the curtains
    • B. use thinner walls
    • C. add loft insulation and double glazing
    • D. open all the windows in winter

  2. Question 2

    A motor is 85% efficient. It is supplied with 1500 J. How much useful energy does it transfer, in J?

    AnswerJ

  3. Question 3

    A device is supplied with 2500 J and transfers 625 J usefully. What is its efficiency, as a percentage?

    Answer%

  4. Question 4

    Why do LED bulbs save money compared with old filament bulbs?

    • A. They are brighter because they are hotter
    • B. They use no electricity
    • C. They are made of glass
    • D. They are more efficient, so less energy is wasted as heat

  5. Question 5

    A motor is 30% efficient. It is supplied with 2000 J. How much useful energy does it transfer, in J?

    AnswerJ

  6. Question 6

    A device is supplied with 800 J and transfers 120 J usefully. What is its efficiency, as a percentage?

    Answer%

  7. Question 7

    Can a device be more than 100% efficient?

    • A. Yes, if it is new
    • B. No, because energy cannot be created
    • C. Yes, if it uses a battery
    • D. Yes, if it is very small

  8. Question 8

    A motor is 90% efficient. It is supplied with 500 J. How much useful energy does it transfer, in J?

    AnswerJ

  9. Question 9

    A device is supplied with 400 J and transfers 160 J usefully. What is its efficiency, as a percentage?

    Answer%

  10. Question 10

    Why do LED bulbs save money compared with old filament bulbs?

    • A. They use no electricity
    • B. They are made of glass
    • C. They are more efficient, so less energy is wasted as heat
    • D. They are brighter because they are hotter

  11. Question 11

    A motor is 35% efficient. It is supplied with 1500 J. How much useful energy does it transfer, in J?

    AnswerJ

  12. Question 12

    A device is supplied with 200 J and transfers 150 J usefully. What is its efficiency, as a percentage?

    Answer%

  13. Question 13

    Can a device be more than 100% efficient?

    • A. No, because energy cannot be created
    • B. Yes, if it uses a battery
    • C. Yes, if it is new
    • D. Yes, if it is very small

  14. Question 14

    A motor is 40% efficient. It is supplied with 1000 J. How much useful energy does it transfer, in J?

    AnswerJ

  15. Question 15

    A device is supplied with 2500 J and transfers 2250 J usefully. What is its efficiency, as a percentage?

    Answer%

  16. Question 16

    An electric motor is 80% efficient. What happens to the other 20%?

    • A. It is mostly wasted heating the motor and its surroundings
    • B. It is stored in the plug
    • C. It is destroyed
    • D. It is turned into extra motion

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  1. add loft insulation and double glazing
  2. 1275 J
  3. 25 %
  4. They are more efficient, so less energy is wasted as heat
  5. 600 J
  6. 15 %
  7. No, because energy cannot be created
  8. 450 J
  9. 40 %
  10. They are more efficient, so less energy is wasted as heat
  11. 525 J
  12. 75 %
  13. No, because energy cannot be created
  14. 400 J
  15. 90 %
  16. It is mostly wasted heating the motor and its surroundings