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1.7 Energy, work and power

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Question 329

The total power input to an electric motor is PPP. The power wasted by the motor is LLL. Which expression gives the percentage efficiency of the motor?

A

P−LP×100%\frac{P - L}{P} \times 100\%PP−L​×100%

B

LP×100%\frac{L}{P} \times 100\%PL​×100%

C

P−LL×100%\frac{P - L}{L} \times 100\%LP−L​×100%

D

P+LP×100%\frac{P + L}{P} \times 100\%PP+L​×100%

Markscheme

1.7 Energy, work and power Questions

  1. IGCSE
  2. /Physics
  3. /1.7 Energy, work and power

533 exam-style questions on CIE IGCSE Physics 1.7 Energy, work and power, covering 1.7.1a Energy stores and energy transfers, 1.7.1b Conservation of energy, 1.7.1c Kinetic and gravitational potential energy, 1.7.2 Work done, 1.7.3 Energy resources, 1.7.3a Energy resources and electricity generation, 1.7.3b Nuclear fusion as an energy source, 1.7.3c Efficiency of energy transfer, and 1.7.4 Power. Each one has a worked solution and a mark scheme showing where the marks go.

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