An engineer records cooling curves for two identical metal casings in the same room. One casing has a matt black finish and the other has a polished finish.
| Casing | Starting temperature (°C) | Lowest recorded temperature (°C) |
|---|---|---|
| matt black | 90 | 60 |
| polished | 80 | 60 |
The temperature of each casing is recorded every minute.
Which method of analysing the results best allows the effect of surface finish to be compared fairly?
Compare the gradient at the moment when each casing begins to cool.
Compare the time each casing takes to cool from its own starting temperature to 60 °C.
Compare the temperature decrease during the first minute for each casing.
Compare the gradients for both casings between 80 °C and 60 °C.
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.