Coulomb's law (kōˈlŏmz) [key], in physics, law stating that the electrostatic force between two charged bodies is proportional to the product of the amount of charge on the bodies divided by the square of the distance between them. If the bodies are oppositely charged, one positive and one negative, they are attracted toward one another; if the bodies are similarly charged, both positive or both negative, the force between them is repulsive (see charge). Coulomb's law applies exactly only when the charged bodies are much smaller than the distance separating them and therefore can be treated approximately as point charges. When combined with principles of quantum physics, Coulomb's law helps describe the forces that bind electrons to an atomic nucleus, that bind atoms together into molecules, and that hold together solids and liquids. The law was deduced in 1785 by C. A. de Coulomb from experimental measures of the forces between charged bodies; the experiments were made using his torsion balance.