# A student shines a beam of white light onto a rough white surface and onto a smooth mirror. Explain the difference in the way the two surfaces reflect the light, and why only one surface produces a clear image.

> Edexcel A-Level Physics (9PH0) — 5.1 Wave properties · Explain · 5 marks

> White light contains all the colours of the visible spectrum. When light strikes a surface, it can be reflected in different ways depending on the texture of that surface.

## Mark scheme (5 marks)

1. The smooth mirror undergoes specular reflection
2. All incident rays hit the smooth surface at the same angle and are reflected at the same angle (law of reflection), so rays leave in the same direction / are parallel
3. The rough white surface undergoes diffuse reflection
4. The rough surface scatters the reflected light in many different directions because the normal varies across the surface
5. Only the smooth mirror produces a clear image because the reflected rays leave in a consistent direction, preserving the pattern of the light / allowing the eye to trace rays back to a single point; the rough surface scatters rays so no consistent image is formed

## Related

- [Revision notes for Edexcel A-Level Physics (9PH0)](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-student-shines-a-beam-of-3eb98e64) · Published by Druglandscape Ltd.