# A ray of light travels from water into air and hits the boundary at an angle to the normal. Explain what happens to the ray as it crosses the boundary, including what happens to its speed, direction, and wavelength.

> Eduqas A-Level Physics — 2.6 Refraction of light · Explain · 5 marks

## Mark scheme (5 marks)

1. The ray speeds up as it crosses from water into air (because air is less optically dense than water)
2. The ray bends/refracts away from the normal
3. The frequency of the light does not change
4. The wavelength increases as the ray enters air
5. The change in speed (and wavelength) causes the change in direction / this is the process of refraction

## Key terms

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

## Related

- [Revision notes for Eduqas A-Level Physics](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)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/a-ray-of-light-travels-from-be9c5a81) · Published by Druglandscape Ltd.