Coulomb's law describes the forces of attraction that exist between two charged particles. If the charges on the particles are and and they are separated by a distance r, then by Coulomb's law
where is the permittivity constant and and are charges measured in coulombs (C), the unit of electrostatic charge. Coulomb's Law, like the law of Universal gravitation, is an inverse square law. The charge on one electron is,
while the charge on one proton is
The charges on electrons and protons are said to be fundamental since no particle has ever been found with a charge of lower magnitude.
