Wave speed

The wave speed is the speed at which a wave propagates through a medium.

Effectively, if we pick any point on the wave, it’s how fast that point moves.

Notation

We usually use the letter v to represent wave speed (for velocity).

Units

Wave speed is measured in metres per second (m/s).

Calculating wave speed

Wave speed can be calculated using the formula:

\text{Wave speed} = \text{Frequency} \times \text{wavelength}

Or, using our symbols:

v = f\lambda

Where:

• v is the wave speed (in metres per second, m/s)
• f is the frequency of the wave (in hertz, Hz)
• \lambda is the wavelength of the wave (in metres, m)

Logically, this makes sense.
If a wave has a high frequency (more waves per second) it must be moving faster. Similarly, if a wave has a long wavelength (more distance between waves), it must also be moving faster.