A body exchanges energy only by radiation. The table shows average powers over two successive intervals.
| Interval | Duration in s\mathrm{s}s | Absorbed power in W\mathrm{W}W | Emitted power in W\mathrm{W}W |
|---|---|---|---|
| first | 40 | 90 | 60 |
| second | 60 | 50 | 80 |
What is the overall change in the body's internal energy?
an increase of 600 J600\,\mathrm{J}600J
a decrease of 3000 J3000\,\mathrm{J}3000J
a decrease of 600 J600\,\mathrm{J}600J
an increase of 3000 J3000\,\mathrm{J}3000J
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.