# Describe what happens to a wave when it undergoes diffraction through a gap, and state the conditions under which the greatest diffraction occurs.

> Cambridge International IGCSE Physics (0625) — 3.1 General properties of waves · Describe · 4 marks

## Mark scheme (4 marks)

1. The wave spreads out / bends around the edges of the gap after passing through it
2. The frequency, wavelength, and speed of the wave are unchanged / remain constant
3. Greatest diffraction occurs when the gap size is of the same order of magnitude as the wavelength / when the gap is approximately equal to the wavelength
4. The narrower the gap (relative to the wavelength) OR the longer the wavelength (relative to the gap size), the greater the diffraction

## Key terms

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

## Related

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