A small metal sphere is suspended in a chamber. Energy is transferred to and from the sphere only by radiation.
A lamp shines steadily at the sphere. The sphere absorbs radiation from the lamp at a constant rate. Its temperature starts to rise.
The table shows three possible pairs of rates of radiation absorption and emission by the sphere.
| Set | Rate of absorption (W) | Rate of emission (W) |
|---|---|---|
| P | 12 | 8 |
| Q | 12 | 12 |
| R | 12 | 15 |
Explain why the temperature of the sphere starts to rise.
Explain which set of rates is consistent with the sphere's temperature staying constant.
106 exam-style questions on AQA GCSE Physics 6.3 Black body radiation, covering 6.3.1 Emission and absorption of infrared radiation and 6.3.2 Perfect black bodies and radiation. Each one has a worked solution and a mark scheme showing where the marks go.