Electron charge, (symbol e), fundamental physical constant expressing the naturally occurring unit of electric charge, equal to 1.6021765 × 10−19 coulombs, or 4.80320451 × 10−10 electrostatic unit (esu, or statcoulomb). In addition to the electron, all freely existing charged subatomic particles up to now discovered have an electrical charge adequate this price or some whole-number multiple of it.
Quarks, which are always bound within larger subatomic particles such as protons and neutrons, have charges of 1/3 or 2/3 of this value.
An electron is discovered by J.J. Thompson in 1897.
