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Wavelength - GCSE Physics Definition

Reviewed by: Leander Oates

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What is wavelength?

In GCSE physics, wavelength is a property of a wave that describes the distance between one point on a wave to the same point on the next wave. Wavelength can be measured from any point on the wave, as long as the same point is used on the following wave. 

In a transverse wave, wavelength can be measured from peak to peak or from trough to trough. In a longitudinal wave, wavelength can be measured from the centre of one compression (or rarefaction) to the centre of the next.

Diagram showing transverse and longitudinal waves. Transverse wave with peaks and troughs, longitudinal wave with compressions and rarefactions, both labelled.
An example of how the wavelength can be measured on a transverse and longitudinal wave

The wavelength of a wave can be calculated using the wave equation in the following form:

lambda equals v over f

Where:

  • lambda= wavelength, measured in metres (m)

  • v = wave speed, measured in metres per second (m/s)

  • f = frequency, measured in hertz (Hz)

The wavelength of a wave is inversely proportional to the frequency of the wave. 

lambda proportional to 1 over f

Therefore, the longer the wavelength, the lower the frequency, and the shorter the wavelength, the higher the frequency.

Diagram of the electromagnetic spectrum showing waves from low energy radio waves to high energy gamma rays, with visible light in the centre.
Waves with a longer wavelength have a lower frequency, and waves with a shorter wavelength have a higher frequency

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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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