# Sonar is used by ships to locate objects on the sea floor. Explain how sonar works, including what type of wave is used and why this wave is suitable for this purpose.

> WJEC A-Level Physics (Wales) — 5.3 Electric and magnetic fields (A-Level only) · Explain · 5 marks

> A ship uses sonar equipment to detect a shipwreck resting on the sea floor. The equipment emits a pulse, detects the returning signal, and calculates the depth of the wreck.

## Mark scheme (5 marks)

1. Sonar uses ultrasound waves
2. A pulse of ultrasound is emitted from the ship
3. The ultrasound reflects off the sea floor / object
4. The reflected pulse is detected and the time taken for the pulse to return is measured
5. Ultrasound is suitable because it can travel through water / it is a longitudinal wave that can travel through fluids

## Key terms

- [sonar](https://www.gradenine.co.uk/glossary/sonar)

## 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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Source: [GradeNine](https://www.gradenine.co.uk/q/sonar-is-used-by-ships-to-98af5681) · Published by Druglandscape Ltd.