# A laser is used in a concert to project patterns and beams of light across a large arena. The laser beam travels a long distance without spreading out, and all the light is the same colour. Explain why laser light is well-suited to this application, referring to the properties of laser light.

> WJEC A-Level Physics (Wales) — 2.8 Lasers · Explain · 5 marks

> In large arenas, lighting designers use lasers rather than ordinary spotlights to create long-distance light effects. The beams remain narrow even when they travel tens of metres across the venue.

## Mark scheme (5 marks)

1. Laser light is coherent / the waves are in phase with each other
2. Laser light is monochromatic / all one wavelength / all one colour / single frequency
3. Laser light is highly collimated / forms a very narrow parallel beam
4. Because the beam does not spread out, it can travel a large distance across the arena and still be seen as a distinct narrow beam
5. Because the light is monochromatic, the beam appears as a single, pure colour which produces a sharp, vivid pattern / is not split into a spectrum

## 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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