# A teacher demonstrates sound waves passing through a narrow gap in a wall. The teacher notices that students on the other side of the wall can hear the sound even when they are standing to the side, not directly in front of the gap. Explain why the students can hear the sound.

> OCR GCSE Physics A: Gateway Science (J249) — P4.1 Wave behaviour · Explain · 4 marks

> A teacher in a school corridor demonstrates that sound can be heard through a narrow gap in a wall, even by students standing at the sides rather than directly opposite the gap.

## Mark scheme (4 marks)

1. The sound waves spread out / bend after passing through the narrow gap
2. This spreading of waves is called diffraction
3. Diffraction is greatest when the gap is similar in size to the wavelength of the wave
4. Because the sound spreads out in all directions beyond the gap, students to the side (not directly in front) can still hear it

## Key terms

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

## Related

- [Revision notes for OCR GCSE Physics A: Gateway Science (J249)](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-teacher-demonstrates-sound-waves-passing-b76a0e07) · Published by Druglandscape Ltd.