A solar cooker contains an interchangeable metal heat store. Two identical heat stores, P and Q, have different surface finishes. One is matt black and the other is shiny silver.
The heat stores exchange energy by radiation. The table shows the average powers measured in two separate tests. Both heat stores start each test at the same temperature.
| test | heat store | average power absorbed in W | average power emitted in W |
|---|---|---|---|
| bright sunlight for 10 minutes | P | 95 | 35 |
| bright sunlight for 10 minutes | Q | 45 | 20 |
| sunlight obscured for 5 minutes | P | 18 | 50 |
| sunlight obscured for 5 minutes | Q | 10 | 24 |
Calculate how much more energy heat store P gains than heat store Q during the test in bright sunlight.
Explain which heat store will be at the higher temperature at the end of the test with the sunlight obscured.
Explain which heat store has the matt black surface.
96 exam-style questions on Edexcel GCSE Physics 5.3 Black body radiation, covering 5.3.1 Emission of radiation and temperature, 5.3.2 Radiation balance and constant temperature, and 5.3.3 The temperature of the Earth. Each one has a worked solution and a mark scheme showing where the marks go.