After his graduation from the Ecole du Genie at Mezieres in 1761, he served as a military engineer in the West Indies and in other obscure French posts. In 1781, he was permanently stationed in Paris and was able to devote more time to research. In 1787 he further proved the inverse-square law for attractive and repulsive forces in both electricity and magnetism, and he later showed that the force is also proportional to the product of the charges, a relationship now called Coulomb's Law . Coulomb may be considered to have extended Newtonian mechanics to a new realm of physics. The unit of electrical charge is named for him.
Coulombic force is one of the principal forces involved in atomic reactions.
Coulomb spent nine years in the West Indies as a military engineer and returned to France with impaired health. Upon the outbreak of the French Revolution, he retired to a small estate at Blois and devoted himself to scientific research. In 1802 he was appointed an inspector of public instruction. Coulomb developed his law as an outgrowth of his attempt to investigate the law of electrical repulsions as stated by Joseph Priestley of England. To this end he invented sensitive apparatus to measure the electrical forces involved in Priestley's law and published his findings in 1785-89.