Two metal targets have the same mass, dimensions and material, but different surface finishes. Target A has a polished silver surface and target B has a matt dark surface.
The table shows results obtained when the targets were tested.
| Target | Percentage of incident infrared radiation reflected | Energy from the target reaching a detector in one minute when the target is at 50 ∘C50\ ^\circ\text{C}50 ∘C |
|---|---|---|
| A | 90% | 12 J |
| B | 15% | 96 J |
Radiation that is not reflected is absorbed by the targets. Each target is initially at 20 ∘C20\ ^\circ\text{C}20 ∘C and is exposed to the same infrared source for a short time. The energy emitted by the targets during this exposure is negligible.
Explain which target will give the greater detector reading immediately after the infrared source is switched off.
106 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.