# Explain how stationary waves are formed in a stretched string fixed at both ends, and describe two ways in which a stationary wave differs from a progressive wave.

> AQA A-Level Physics (7408) — 3.3.1 Progressive and Stationary Waves · Explain · 5 marks

> When a stretched string fixed at both ends is plucked, a stationary wave pattern can be formed.

## Mark scheme (5 marks)

1. A wave travels along the string and reflects at the fixed end / boundary
2. The incident wave and the reflected wave overlap / superpose / travel in opposite directions
3. A stationary wave does not transfer energy (along the string / between the fixed ends), whereas a progressive wave does transfer energy
4. In a stationary wave, different points vibrate with different amplitudes (some points do not vibrate at all — nodes — and some vibrate with maximum amplitude — antinodes), whereas in a progressive wave all points have the same amplitude
5. In a stationary wave, all points between two adjacent nodes oscillate in phase with each other (points on opposite sides of a node are in antiphase), whereas in a progressive wave there is a continuous phase change along the wave

## Key terms

- [stationary wave](https://www.gradenine.co.uk/glossary/stationary-wave)
- [progressive wave](https://www.gradenine.co.uk/glossary/progressive-wave)

## Related

- [Revision notes for AQA A-Level Physics (7408)](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/explain-how-stationary-waves-are-formed-9f1d83ed) · Published by Druglandscape Ltd.