The Table shows the power ratings of four appliances in a kitchen.
Table
| Appliance | Power rating in W\text{W}W |
|---|---|
| kettle | 2400 |
| toaster | 1200 |
| microwave oven | 800 |
| LED lamp | 8 |
Which appliance transfers energy at the slowest rate?
The toaster is switched on for 150 s.
Use the equation: energy transferred=power×time\text{energy transferred} = \text{power} \times \text{time}energy transferred=power×time
Calculate the energy transferred by the toaster.
The kettle and the microwave oven are each used to heat the same mass of water by the same temperature rise.
Assume that no energy is wasted.
Explain which appliance heats the water in less time.
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.