A microwave oven has a power rating of 1.2 kW. It is used for 5.0 minutes.
A lamp has a power rating of 60 W.
Use the equation:
energy transferred=power×time\text{energy transferred} = \text{power} \times \text{time}energy transferred=power×time
How long must the lamp be switched on to transfer the same amount of energy as the microwave oven?
100100100 minutes
202020 minutes
0.250.250.25 minutes
600060006000 minutes
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.