An LED is a type of electroluminescent light source that emits light when current flows through a semiconductor material.

  • An LED typically emits light of a single colour that is composed of a narrow range of wavelengths.
  • Multicoloured LEDs typically have three diodes that emit red, green, and blue light.
  • By adjusting the relative brightness of the primary colours, a multicoloured LED can create a vast array of colours.
  • By combining the three primary colours of red, green, and blue light in equal proportions multicoloured LEDs can produce white light.
  • Typical peak wavelengths for multicoloured LEDs might be red = 625 nanometres, green = 500 nm, blue = 440 nm.
  • LED light sources are commonly used to demonstrate the effects of projecting additive primary colours onto a dark surface.