An electric fan is powered from the mains. Some of the energy supplied to the motor of the fan is wasted.
Which statement describes how energy is wasted in the motor?
Current heats the coils, and friction gives the blades extra kinetic energy
Friction heats the moving parts, and the magnets store energy from the current
Current heats the coils, and friction between the moving parts heats the motor
Current in the coils is used up, so less current returns to the mains supply
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.