GCSE Physics

Speed, Frequency & Wavelength

The relationship between the speed, frequency and wavelength is best found from a simple example.

Isobel sets up a ripple tank to produce 2 waves each second (i.e. frequency = 2 Hz). She times the waves 2 s to travel the 100 cm distance to the other side of the tank. She measures the distance between the waves as 25 cm: this is the wavelength.

A frequency of 2 Hz means one wave is produced every 0.5 s (this is known as the time period of the waves and is 1÷frequency).

In 0.5 s, waves move 25 cm, so we can find the speed using:

speed = distance / time = wavelength / time period = 25 cm / 0.5 s = 50 cm/s

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