Waves transfer energy but not matter. Waves may be transverse (eg water wave) or longitudinal (eg sound wave). Wave motion can be described using the terms amplitude, wavelength, frequency and period.

The time period of a wave can be calculated using the equation:

This is when:

- time period (T) is measured in seconds (s)
- frequency (f) is measured in Hertz (Hz)

Calculate the time period of a wave with a frequency of 50 Hz.

- Question
Calculate the frequency of a wave with a time period of 0.05 seconds.

The speed of a wave can be calculated using the equation:

wave speed = frequency × wavelength

This is when:

- wave speed (v) is measured in metres per second (m/s)
- frequency (f) is measured in Hertz (Hz)
- wavelength ( ) is measured in metres (m)

The equation shows that wavelength is directly proportional to velocity of a wave which is moving at a constant frequency (for example, when water waves are refracted in a ripple tank).

What is the speed of a wave that has a frequency of 50 Hz and a wavelength of 6 m?

- Question
What is the frequency of a wave with a speed of 5 m/s and a wavelength of 25 m?