Wave features

Amplitude

As waves travel, they set up patterns of disturbance.

The amplitude of a wave is its maximum disturbance from its undisturbed position.

curriculum-key-fact
It is important to note that the amplitude is not the distance between the top and bottom of a wave.
A wave shape drawn on an unlabelled graph. The amplitude and wavelength of the wave are labelled and shown using arrows.

Wavelength λ

The wavelength of a wave is the distance between a point on one wave and the same point on the next wave.

It is often easiest to measure this from the trough of one wave to the trough of the next wave, or from thecrest of one wave to the crest of the next wave.

But it doesn't matter where you measure it - as long as it is the same point on each wave.

The symbol for wavelength is the Greek letter lambda, λ.

Frequency f

The frequency of a wave is the number of waves produced by a source each second.

It is also the number of waves that pass a certain point each second.

The unit of frequency is the hertz (Hz).

It is common for kilohertz (kHz), megahertz (MHz) and gigahertz (GHz) to be used when waves have very high frequencies.

For example:

  • most people cannot hear a high-pitched sound above 20 kHz;
  • radio stations broadcast radio waves with frequencies of about 100 MHz;
  • most wireless computer networks operate at 2.4 GHz.

(Remember kilo k = 103 mega M = 106 giga G = 109)

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

\text{frequency f =}~\frac{\text{number of waves to pass a point}}{\text{time taken in seconds}}