# Explain what happens to the speed, wavelength, and direction of a ray of white light as it passes from glass into air, and explain why white light separates into a spectrum of colours during this process.

> AQA A-Level Physics (7408) — 3.3.2 Refraction, Diffraction and Interference · Explain · 5 marks

## Mark scheme (5 marks)

1. The light speeds up when moving from glass (denser) into air (less dense).
2. The wavelength increases as the light enters air.
3. The ray bends away from the normal as it enters air.
4. Different wavelengths (colours) of light slow down by different amounts in glass / speed up by different amounts when leaving glass.
5. Because each colour refracts by a different amount, they emerge at different angles, spreading out to form a spectrum.

## Key terms

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

## Related

- [Revision notes for AQA A-Level Physics (7408)](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/explain-what-happens-to-the-speed-b16082f3) · Published by Druglandscape Ltd.