# A star emits radiation across a range of wavelengths. As the star cools over billions of years, explain how the radiation it emits changes.

> AQA GCSE Physics (8463) — 4.6.3 Black body radiation (Phys only) · Explain · 4 marks

> Stars behave as perfect black bodies. A particular star is observed to gradually decrease in surface temperature over a very long period of time.

## Mark scheme (4 marks)

1. A perfect black body absorbs all radiation incident on it (and does not reflect or transmit any radiation)
2. As temperature decreases, the total amount / intensity of radiation emitted decreases
3. The peak of the emitted radiation shifts to longer wavelengths (as temperature decreases)
4. The star emits radiation that is more concentrated in / towards the infrared region of the electromagnetic spectrum

## Key terms

- [wavelength](https://www.gradenine.co.uk/glossary/wavelength)

## Related

- [Revision notes for AQA GCSE Physics (8463)](https://www.gradenine.co.uk/learn)
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Source: [GradeNine](https://www.gradenine.co.uk/q/a-star-emits-radiation-across-a-69f44836) · Published by Druglandscape Ltd.