A steel bar is heated in a furnace. It first glows dull red, and then glows bright yellow-white as it becomes hotter. This change in colour happens because, as the temperature of the bar rises,
it reflects more of the light falling on it from the furnace walls.
more of the radiation it emits is at shorter wavelengths.
more of the radiation it emits is at longer wavelengths.
it stops emitting infrared radiation and emits only visible light.
40 exam-style questions on AQA GCSE Physics 6.3 Black body radiation, covering 6.3.1 Emission and absorption of infrared radiation and 6.3.2 Perfect black bodies and radiation. Each one has a worked solution and a mark scheme showing where the marks go.