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8 Energy – forces doing work

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Question 10

An emergency lighting unit receives an input power of 300 W. A converter in the unit is 75% efficient and supplies power to a lamp. The lamp transfers 90 W usefully as light. What is the efficiency of the lamp?

[1]
A

40%40\%40%

B

45%45\%45%

C

75%75\%75%

D

30%30\%30%

Markscheme

8 Energy – forces doing work Questions

  1. GCSE
  2. /Physics
  3. /8 Energy – forces doing work

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