Electronvolt (unit)

Last revised by Dr Daniel J Bell on 07 May 2022

An electronvolt (eV) is defined as the energy required to accelerate a single electron at rest through an electron potential difference of one volt in a vacuum.

1 eV ≈ 1.603 x 10-19 J

Electronvolts are a more mathematically convenient method to describe the miniscule quantity of energy associated with photons in imaging physics.

The energy required in diagnostic x-rays falls within the range of kiloelectronvolts (keV), whereas the higher energy required in radiotherapy is often expressed in megaelectronvolts (MeV).

See also

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