# Explain how a laser produces a beam of light that is different from the light produced by an ordinary light bulb.

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

> Lasers are used in many everyday applications, from barcode scanners to medical procedures. The light they produce has special properties that make them useful.

## Mark scheme (5 marks)

1. Laser light is coherent / all waves are in phase with each other
2. Laser light is monochromatic / all one wavelength (or frequency / colour)
3. Laser light is collimated / the beam does not spread out (unlike an ordinary bulb)
4. An ordinary light bulb emits light of many different wavelengths / is not monochromatic
5. An ordinary light bulb emits light in all directions / waves are not in phase / is not coherent

## 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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