| An electronvolt (symbol eV) is (technically) the amount of kinetic energy gained by a single unbound electron when it passes through an electrostatic potential difference of one volt, in vacuum. The one-word spelling is the modern recommendation although the use of the earlier electron volt still exists. It is used to represent either very small amounts of energy or very small masses. |
| Einstein reasoned that energy is equivalent to (rest) mass, as famously expressed in the formula E=mc2. It is thus common in particle physics, where mass and energy are often interchanged, to use eV/c2 or even simply eV as a unit of mass. (Although the latter is only strictly valid when working in natural units where c=1.) |
| One electronvolt is a very small amount of energy: |
| 1 eV = 1.602 176 53 (14) x 10-19 Joules. |
| KeV = 1 thousand electron volts; 1 x 103 eV |
| MeV = 1 million electron volts; 1 x 106 eV |
| GeV = 1 billion electron volts; 1 x 109 eV |
|
| Total (on average) energy released in nuclear fission of one
U-235
atom is; 3.2 x 10-11 joules or 200 MeV. |
| Total (on average) energy released in fission of one
Pu-239
atom is; 3.5 x 10-11 joules or 210 MeV. |