# A student uses a micrometer screw gauge rather than a ruler to measure the diameter of a thin copper wire. Explain why the micrometer screw gauge is more suitable for this measurement, and state one advantage of using a digital device rather than an analogue device when taking this reading.

> Cambridge International IGCSE Physics (0625) — 1.1 Physical quantities and measurement techniques · Explain · 4 marks

## Mark scheme (4 marks)

1. The wire's diameter is very small / too small to measure accurately with a ruler
2. The micrometer screw gauge can measure to 0.01 mm / measures very small distances accurately
3. A digital device displays the measurement directly on a display (no scale to read)
4. Using a digital device reduces / removes the risk of parallax error / human reading error

## Key terms

- [micrometer screw gauge](https://www.gradenine.co.uk/glossary/micrometer-screw-gauge)
- [analogue device](https://www.gradenine.co.uk/glossary/analogue-device)
- [digital device](https://www.gradenine.co.uk/glossary/digital-device)

## Related

- [Revision notes for Cambridge International IGCSE Physics (0625)](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-uses-a-micrometer-screw-c91cbe04) · Published by Druglandscape Ltd.