A laboratory tests two small circular metal samples of the same size at the same temperature.
The surface of sample A behaves as a perfect black body. The surface of sample B has a grey finish.
A calibration for the infrared detector gave these results for the same heated reference source.
| Distance between source and detector in cm | Detector reading in arbitrary units |
|---|---|
| 20 | 64 |
| 40 | 16 |
The samples were then tested.
| Sample | Distance between sample and detector in cm | Detector reading in arbitrary units |
|---|---|---|
| A | 40 | 36 |
| B | 20 | 48 |
A student concludes that sample B is the better emitter because its detector reading is higher.
Calculate the detector reading expected for sample B if the detector had been 40 cm from the sample.
Evaluate the student's conclusion. Use your answer to part (a) and ideas about perfect black bodies.
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.