Two kettles heat equal masses of water through the same temperature rise. The table shows their electrical power and the fraction of input energy transferred to the water.
| Kettle | Power in kW\mathrm{kW}kW | Fraction transferred to water |
|---|---|---|
| P | 2.0 | 0.80 |
| Q | 2.5 | 0.64 |
Which comparison is correct?
Both take the same time; Q receives more electrical energy.
Both take the same time; P receives more electrical energy.
Q takes less time; both receive equal electrical energy.
P takes less time; both receive equal electrical energy.
81 exam-style questions on Edexcel GCSE Physics 10.4 Mains electricity, covering 10.4.1 Direct and alternating current, 10.4.2 Live, neutral and earth wires; safety, 10.4.3 Mains wire potential differences and dangers, and 10.4.4 Power ratings and energy use. Each one has a worked solution and a mark scheme showing where the marks go.