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Amplitude - GCSE Physics Definition

Reviewed by: Leander Oates

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What is amplitude?

In GCSE physics, the amplitude of a wave is the distance between the peak or trough and the undisturbed position. 

Diagram of a wave illustrating wavelength (λ) and amplitude (A) with arrows, axes labelled displacement (x) and distance of wave travel.

The amplitude of the wave is the distance between the peak of the wave and its undisturbed position. The undisturbed position lies along the x-axis.

Amplitude is sometimes described as the maximum displacement from the undisturbed position. 

If you imagine the wave as a water wave, the undisturbed position is the flat, completely calm water. The amplitude measures how far away from this flat position the highest or lowest points on the wave are. 

Amplitude is related to the amount of energy a wave transfers. For example, the greater the amplitude of a sound wave, the greater its volume. 

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Leander Oates

Reviewer: Leander Oates

Expertise: Physics Content Creator

Leander graduated with First-class honours in Science and Education from Sheffield Hallam University. She won the prestigious Lord Robert Winston Solomon Lipson Prize in recognition of her dedication to science and teaching excellence. After teaching and tutoring both science and maths students, Leander now brings this passion for helping young people reach their potential to her work at SME.

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