Wavelength

The diagram shows the wavelength of a wave. This is the distance from one peak to the next peak. In practice the measurement can be made between any two similar points on the wave form.

Frequency

If you sat on a boat and counted the number of waves which pass under the boat in a given time you would be measuring the frequency. Frequency is measured in hertz (Hz) which are the number of waves in 1 second.

Velocity

Velocity measures how far the wave travels in a given time. This is normally measured in metres per second. Waves on water might travel at a few metres per second, sound waves travel at around 340 metres per second in air and light in a vacuum travels at around 300 million metres per second.

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