A factory tests three identical metal access panels for a heated enclosure. Each panel has a different surface finish and is kept at the same operating temperature.
| Surface finish | Infrared energy emitted in 3.0 min |
|---|---|
| matt black | 9.0 kJ |
| gloss white | 6.3 kJ |
| shiny silver | 1.8 kJ |
The average power emitted as infrared radiation must be no more than 30 W.
Calculate which surface finishes meet this requirement. Show your working.
Explain why the manufacturer cannot assume that this finish will still meet the requirement if the operating temperature is increased.
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.