# Explain why a ray of light changes direction when it passes from air into glass.

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

> A ray of light travelling through air enters a glass block. The ray bends towards the normal as it crosses the boundary.

## Mark scheme (5 marks)

1. Light slows down when it enters glass (a denser medium)
2. The wavelength of light decreases as it enters the glass
3. The frequency of the light stays the same / does not change
4. The ray bends towards the normal because it is entering a denser medium
5. This change in direction is called refraction

## 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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