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:

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.

flashcards

QuestionAnswer
What symbol is used for wave speed?v (for velocity)
What units is wave speed measured in?Metres per second (m/s)
Write the formula that relates wave speed, frequency, and wavelength.v = f\lambda
What does each symbol in v = f\lambda represent?v = wave speed (m/s), f = frequency (Hz), \lambda = wavelength (m)
Why does a higher frequency mean a faster wave speed?More waves pass per second, so the wave must be moving faster.
Why does a longer wavelength mean a faster wave speed?If there is more distance between wave peaks, the wave must move faster to cover that distance in the same time.