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1.7 Energy, work and power

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Question 158

An electric motor has a power input of 8.0 W. It wastes 2.0 W of power as heat and sound.

What is the efficiency of the motor?

A

25%25\%25%

B

60%60\%60%

C

75%75\%75%

D

133%133\%133%

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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