Photon energy

Photon energy is the energy carried by a single photon. The amount of energy is inversely proportional to the wavelength and directly proportional to the photon’s electromagnetic frequency.

  • The higher the photon’s frequency, the higher it’s energy. Equivalently, the longer the photon’s wavelength, the lower it’s energy.
  • Photon energy is solely a function of the photon’s wavelength and frequency.
  • Other factors, such as the intensity of the radiation, do not affect photon energy. In other words, two photons of light with the same colour and therefore, same frequency, will have the same photon energy, even if one was emitted from a wax candle and the other from the Sun.
  • Units of energy commonly used to denote photon energy are the electronvolt (eV) and the joule.