An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt.
This is a very small amount of energy:
- 1 eV ≈ 1.602 × 10-19 J.
In particle physics
, the megaelectronvolt
(1 MeV = 106
eV) is also used to measure masses of elementary particles, using the conversion from special relativity
- E = m c2
stands for energy, m
for mass and c
for the speed of light in vacuum
In these units, the mass of an electron
is about 0.5 MeV
, and that of a proton
is about 940 MeV
For comparison, charged particles in a nuclear explosion range from 0.3 to 3 MeV. The typical atmospheric molecule has an energy of about 0.03 eV.
To convert a particle's energy in electronvolts into its temperature in kelvin, divide by 11,604. See also: Orders of magnitude