The coulomb (C) is a meter-kilogram-second unit of electrical energy. It is equal to the transferred electrical charge provided within one second by a constantcurrent of 1 ampere, i.e. one ampere-second (As) or 1C. Coulomb is named after the French physicist Charles Augustin de Coulomb (1736 to 1806), who formulated Coulomb's law
. The unit Coulomb and the elementary charge are directly related to each other: 1 Coulomb corresponds to an elementary charge of 6.24 x 10exp18 electrons. Conversely, it follows that the reciprocal value corresponds to the charge of an electron: namely 1.6 x 10exp-19.
Coulomb's law describes the force between two point charges
If two point charges Q1 and Q2 are at a distance "r", they are attracted or repelled from each other by a force "F". The force (Fr) is given by Coulomb's law. Here, (Epsilon) = 8.85419x10exp-12 As/Vm is the absolute dielectric constant