Waves are one way in which energy may be transferred between stores. Both mechanical and electromagnetic waves will transfer energy but not matter.

Part of

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 5 Hz.

- Question
Calculate the time period of a wave with a frequency of 400 Hz.

Wave velocity, the speed of a wave, can be calculated using the equation:

wave speed = frequency × wavelength

This is when:

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

What is the wave speed if the frequency is 50 Hz and the wavelength is 6 m?

- Question
What is the speed of a wave with a frequency of 0.2 Hz and a wavelength of 25 m?

Sound is a mechanical longitudinal wave. The wave is passed on by collisions between particles, so the speed the wave moves depends on the density of the particles.

Medium | State | Speed of sound |
---|---|---|

Steel | Solid | 6,000 m/s |

Water | Liquid | 1,500 m/s |

Air | Gas | 330 m/s |

When sound moves from one medium into another, the change in speed will also cause a change in wavelength, frequency is unaffected.

wave speed = frequency × wavelength

Constant frequency means that the wavelength will be proportional to the wave velocity.