Wavelength is a measurement from any point on the path of a wave to the same point on its next oscillation. The measurement is made parallel to the centre-line of the wave.

  • The wavelength of an electromagnetic wave is measured in metres.
  • Each type of electromagnetic radiation, such as radio waves, visible light and gamma waves,  forms a band of wavelengths on the electromagnetic spectrum.
  • The visible part of the electromagnetic spectrum is composed of the range of wavelengths that correspond with all the different colours we see in the world.
  • Human beings don’t see wavelengths of visible light, but they do see the spectral colours that correspond with each wavelength and the other colours produced when different wavelengths are combined.
  • The wavelength of visible light is measured in nanometres. There are 1,000,000,000 nanometres to a metre.