An Etymological Dictionary of Astronomy and Astrophysics

The unit of electric charge in the → cgs system of units. Also called the → statcoulomb. The esu is defined such that if two objects, each carrying a charge of +1 esu, are 1 cm aparat, then they repel each other with a force of 1 → dyne. 1 esu = 3.3356 × 10^-10 → coulombs.

See also: → electrostatic; → unit; → charge.