Coulomb’s law states that electrostatic force varies inversely with the square of the distance between two point charges.
The law also says that the force is proportional to the product of the two charges. Like charges repel, while unlike charges attract. In vacuum, its mathematical form includes the constant 1/(4πε₀), where ε₀ is the vacuum permittivity.
Charles-Augustin de Coulomb established this relationship in the 1780s using a torsion balance. His experiments helped put electrostatics on a quantitative foundation. The inverse-square pattern resembles the distance dependence of gravity, although electric forces can be attractive or repulsive.
Coulomb’s law is most directly applied to idealized point charges. For extended objects or complicated charge distributions, physicists divide the charge into small elements and add their effects using superposition.