Frequency, Wavelength and Amplitude

Definition of Terms

Frequency (f) refers to the number of complete cycles of a wave passing a specific point in one second. The unit of frequency is Hertz (Hz).
The wavelength (λ) defines the length of one full cycle of a wave. This can be measured from any point on a wave to the equivalent point on the next wave.
The amplitude (A) is the maximum displacement from the undisturbed or equilibrium position.

They are interrelated by the formula v = f × λ, where v is the wave speed, f is the frequency, and λ is the wavelength.
Frequency and wavelength are inversely proportional - if the frequency of a wave increases, the wavelength decreases, provided the speed of the wave remains constant.

The energy carried by a wave is related to its amplitude. A wave of greater amplitude will carry more energy.

Changing the frequency of a wave will modify the wavelength but not the amplitude.
Changing the amplitude of a wave will not affect the frequency or wavelength. However, it will change the energy carried by the wave.
Changing the wave speed (for instance, when a wave moves from one medium to another) will affect the wavelength and possibly the direction of the wave (through refraction), but it does not affect the frequency or amplitude of the wave.

These wave characteristics are crucial in a variety of applications, for instance:
- Frequency determines the pitch of a sound wave and the colour of a light wave.
- The amplitude of sound waves relates to loudness and in light waves to brightness/intensity.
- Wavelength and frequency are exploited in communication systems, selection of radio stations, medical imaging and many other technologies.