An electronvolt is a unit of energy commonly used to measure the energy carried by electromagnetic radiation.

  • Electronvolts can be used for measurements at the scale of elementary particles as small as single photons, the quantum of the electromagnetic field.
  • One electronvolt is the amount of energy that a single electron has when it is accelerated by a potential difference of 1 volt.
  • If there is a difference in voltage of 1 volt between two points in an electrical circuit (within a capacitor for example) then the force required (and the energy gained) by a photon accelerating from one point to the other is 1 electronvolt.