7.1.5—V = f λ

For a progressive wave, v=fλ: the wave speed equals frequency multiplied by wavelength.

If the medium fixes v, a change in source frequency changes wavelength inversely. Use metres and hertz so the result is m s⁻¹.

If a wave travels at 12 m s⁻¹ with frequency 4.0 Hz, its wavelength is 3.0 m.

The wave speed is not the same as the speed of individual particles oscillating in the medium.