# A star like the Sun behaves as a black body. Explain how the temperature of a star is related to the radiation it emits, and describe what this tells us about the colour of stars that are hotter than the Sun.

> WJEC A-Level Physics (Wales) — 6.3 Stellar evolution and cosmology (A-Level only) · Explain · 5 marks

> Stars emit electromagnetic radiation across a range of frequencies. The peak frequency of radiation emitted by a star depends on its surface temperature. The Sun appears yellow-white and has a surface temperature of approximately 5500 °C. Some stars are significantly hotter than the Sun.

## Mark scheme (5 marks)

1. A black body absorbs all radiation incident on it (and is also an ideal emitter)
2. The hotter the star, the greater the power / intensity of radiation emitted
3. The hotter the star, the higher the peak frequency of radiation emitted
4. Stars hotter than the Sun emit peak radiation at higher frequencies, towards the blue/violet end of the visible spectrum
5. Cooler stars emit peak radiation at lower frequencies, towards the red end of the visible spectrum, so colour indicates temperature

## Key terms

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

## Related

- [Revision notes for WJEC A-Level Physics (Wales)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-star-like-the-sun-behaves-7ba0c6f0) · Published by Druglandscape Ltd.