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Coulomb, Charles (Augustin de)

law attraction coulomb’s proportional

[koolõb] (1736–1806) French physicist: discovered inverse square law of electric and magnetic attraction.

Coulomb trained as a military engineer and served in Martinique for 9 years. He eventually returned to France as an engineering consultant but resigned from the Army altogether in 1791 and moved from engineering to physics. During the French Revolution he was obliged to leave Paris, but returned under Napoleon and became an inspector-general of Public Instruction.

Not surprisingly in view of his military service, much of Coulomb’s early work was concerned with engineering problems in statics and mechanics. He showed that friction is proportional to normal pressure (Coulomb’s Law of Friction) and introduced the concept of the thrust line. However, he is primarily remembered for his work on electrical and magnetic attraction and repulsion. From 1784 onwards he conducted a series of very delicate experiments, using a torsion balance he had invented himself and capable of detecting forces equivalent to 10 –5 g . He discovered that the force between two charged poles is inversely proportional to the square of the distance between them and directly proportional to the product of their magnitude (Coulomb’s Law of Force). This was a major result, paralleling law of gravitational attraction. The SI unit of electric charge, the coulomb ©, is named in his honour. It is the charge crossing any section of a conductor in which a steady current of 1 ampere flows for 1 second.

Coulson, Charles Alfred [next] [back] Cotton Candy

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