Properties of Waves

The four main wave properties are:

  • Wavelength
  • Amplitude
  • Frequency
  • Period

Below you can see two displacement-time graphs which show the properties of waves:

  • Keep in mind, that displacement is how far from the equilibrium point the wave has oscillated.


Wavelength (λ) is the distance between two peaks which are next to each other, or any two identical points which are next to each other. In the diagram above, the wavelength is measured at the midpoint, not the peak.


Amplitude is the maximum displacement of a point on the wave. It is the distance between the midpoint and the peak of the wave, or the midpoint and the trough of the wave.


Frequency is the number of complete waves passing a point in a second. The wave equation below shows how wave speed, frequency and wavelength are related.

  • v = Wave speed in metres per second (m/s)
  • f = Frequency in hertz (Hz)
  • λ (lambda) = Wavelength in metres (m)

Time Period

The time period of a wave is the time taken for a full cycle of a wave. This can be calculated when the frequency value is known. The equation to work out the time period of a wave is:

  • T = Time period in seconds (s)
  • f = Frequency in hertz (Hz)


A wave has a wave speed of 255 m/s and a wavelength of 15 m. Calculate the time period of the wave.

Step 1: Write down the known values

Wave speed = 255 m/s

Wavelength  = 15 m

Step 2: Put the known values into the equation to calculate the frequency

We know that wave speed = frequency × wavelength

By rearranging the equation, we can calculate the frequency. So, frequency = \frac{wave\:speed}{wavelength}

Frequency = \frac{255}{15}

= 17 Hz

Step 3: Put the known values into the equation to calculate the time period

Time period = \frac{1}{frequency}

= \frac{1}{17}

Time period = 0.0588 s (3 s.f.)