A camera sensor is tested inside an evacuated enclosure. The test is arranged so that energy is transferred to and from the sensor only by radiation.
During the first stage, the sensor gains 600 J of energy. During the next 40 s, it absorbs radiation at an average power of 55 W.
The sensor must return to its initial internal energy at the end of the test. The emission controller has four settings: 15 W, 40 W, 55 W and 70 W.
What is the average power at which the sensor must emit radiation during the second stage?
15 W15\,\mathrm{W}15W
55 W55\,\mathrm{W}55W
40 W40\,\mathrm{W}40W
70 W70\,\mathrm{W}70W
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.