# A surgeon uses a laser to cut through tissue during an operation. Explain why a laser beam is more suitable for this purpose than a scalpel blade, referring to the properties of laser light in your answer.

> Eduqas A-Level Physics — 2.8 Lasers · Explain · 5 marks

> Lasers are used in many medical procedures. Unlike a scalpel, a laser beam can be focused to an extremely small point and delivers energy directly to the tissue.

## Mark scheme (5 marks)

1. Laser light is monochromatic (all one wavelength/frequency)
2. Laser light is coherent (waves are in phase / peaks and troughs line up)
3. Laser light is highly collimated / does not spread out, so it can be focused to a very small (precise) point
4. The concentrated energy at the focused point is high enough to cut/vaporise tissue
5. The laser cauterises (seals) blood vessels as it cuts, reducing bleeding compared to a scalpel

## 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)
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