An aerospace engineer is investigating how different surface finishes affect the rate of infrared radiation emitted by a spacecraft's external hull panel.
They use a hollow metal cube equipped with an electric heater underneath to heat and maintain all vertical faces at a constant, uniform temperature. Each vertical face has a different surface finish: rough black, matt white, dull grey alloy, and polished copper.
A calibrated thermopile sensor (infrared detector) is used to measure the thermal irradiance emitted from each surface, as shown in the diagram below:
The table below shows the results of the investigation:
| Surface Finish | Irradiance in W m−2\text{W m}^{-2}W m−2 |
|---|---|
| Rough black | 450.8 |
| Matt white | 412.3 |
| Dull grey alloy | 185.2 |
| Polished copper | 35.4 |
In this investigation, the surface finish is the ________ variable. Choose from: control, dependent, independent.
Based on the values in the table, what is the resolution of the thermopile sensor? Include the unit in your answer.
Describe how the engineer should use this equipment to make a valid comparison of the infrared radiation emitted from each of the four vertical surfaces.
Give one conclusion about the emission of infrared radiation that can be made from these results.
Black body radiation (physics only) Questions
Practise AQA GCSE Physics Black body radiation (physics only) with exam-style questions for Foundation and Higher tier. 9 questions covering Emission and absorption of infrared radiation and Perfect black bodies and radiation, matched to the AQA GCSE Physics (8463) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.