An aerospace engineer is designing passive thermal control systems for a small satellite. They want to investigate how the surface finish of exterior panels affects the rate at which they emit thermal infrared radiation.
The engineer prepares four identical aluminum plates, each coated with a different surface finish:
- Matte black paint
- Matte white paint
- Anodized grey aluminum
- Polished gold plating
Each plate in turn is mounted onto a heated copper block maintained at a constant internal temperature. A digital thermal imaging radiometer is placed at a fixed distance d d\,d from the plate to measure the emitted infrared power density (irradiance) in watts per square meter (W m−2\text{W m}^{-2}W m−2).
The table below shows the results of the investigation:
| Surface finish | Emitted thermal irradiance in W m−2\text{W m}^{-2}W m−2 |
|---|---|
| Matte black paint | 450.3 |
| Matte white paint | 425.8 |
| Anodized grey aluminum | 380.5 |
| Polished gold plating | 52.1 |
In this investigation, the surface finish of the plates is the ________ variable. Choose from: control, dependent, independent.
Based on the values in the table, what is the resolution of the digital thermal imaging radiometer?
Describe how the engineer should set up and use this apparatus to ensure a valid comparison of the infrared radiation emitted by the four different surface finishes.
State one conclusion regarding the emission of infrared radiation by different surface finishes that can be drawn 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.