Definition of a Coulomb

Charge is measured in coulombs, a rather bizarre unit of charge. One proton has a charge of 1.602x10-19 C. The choice of the unit of charge will appear slightly more convenient when we study magnetism later in the course. The charge on electrons and protons, which are equal and opposite, are noted as e:

e = 1.602x10-19 Coulombs

Examples        Coulomb's law index