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7.2 Power and efficiency

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Question 12
H

An electric drill is connected to the mains supply and switched on.

Which statement describes the useful and the wasted energy transfers?

[1]
A

Useful: to thermal stores of the motor. Wasted: to the kinetic store of the drill bit

B

Useful: to the kinetic store of the drill bit. Wasted: to the chemical store of the motor

C

Useful: to the kinetic store of the drill bit. Wasted: to thermal stores and by sound

D

Useful: to the kinetic store and by sound. Wasted: back to the electrical store of the mains

Markscheme

7.2 Power and efficiency Questions

  1. GCSE
  2. /Physics
  3. /7.2 Power and efficiency

50 exam-style questions on OCR GCSE Physics 7.2 Power and efficiency, covering 7.2.1 Dissipation of energy, 7.2.2 Energy transfers in domestic devices, 7.2.3 Power ratings of domestic appliances, 7.2.4 Efficiency of energy transfers, 7.2.5 Ways to increase efficiency, 7.2.6 Reducing unwanted energy transfers, and 7.2.7 Thermal conductivity and the cooling of buildings. Each one has a worked solution and a mark scheme showing where the marks go.

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