Charles-Augustin de Coulomb
Charles Augustin de Coulomb (June 14, 1736 – August 23, 1806) was a French physicist.
Coulomb was born in Angoulême, France. He chose the profession of military engineer, and spent three years, to the decided injury of his health, at Fort Bourbon, Martinique. Upon his return, he was employed at La Rochelle, the Isle of Aix and Cherbourg. He discovered an inverse relationship on the force between charges and the square of its distance, later named after him as Coulomb's law.
In 1781, he was stationed permanently at Paris. On the outbreak of the Revolution in 1789, he resigned his appointment as intendant des eaux et fontaines, and retired to a small estate which he possessed at Blois. He was recalled to Paris for a time in order to take part in the new determination of weights and measures, which had been decreed by the Revolutionary government. Of the National Institute he was one of the first members; and he was appointed inspector of public instruction in 1802. But his health was already very feeble, and four years later he died in Paris.
Coulomb is distinguished in the history of mechanics and of electricity and magnetism. In 1779 he published an important investigation of the laws of friction (Théorie des machines simples, en ayant égard au frottement de leurs parties et à la roideur des cordages), which was followed twenty years later by a memoir on viscosity.
In 1784 his Recherches théoriques et expérimentales sur la force de torsion et sur l'élasticité des fils de metal (Histoire de l’Académie Royale des Sciences, 229-269, 1784) appeared. This memoir contained a description of different forms of his torsion balance. He used the instrument with great success for the experimental investigation of the distribution of charge on surfaces, of the laws of electrical and magnetic force, and of the mathematical theory of which he may also be regarded as the founder.
In 1785 Coulomb presented his three reports on Electricity and Magnetism:
- Premier Mémoire sur l’Electricité et le Magnétisme, Histoire de l’Académie Royale des Sciences, 569-577, 1785. In this publication Coulomb describes “How to construct and use an electric balance (torsion balance) based on the property of the metal wires of having a reaction torsion force proportional to the torsion angle”. Coulomb also determinates experimentally the law that explains how “two bodies electrified of the same kind of Electricity exert on each other”.
- Sécond Mémoire sur l’Electricité et le Magnétisme, Histoire de l’Académie Royale des Sciences, 578-611, 1785. In this publication Coulomb carries out the “determination according to which laws both the Magnetic and the Electric fluids act, either by repulsion or by attraction”.
- Troisième Mémoire sur l’Electricité et le Magnétisme, Histoire de l’Académie Royale des Sciences, 612-638, 1785. “On the quantity of Electricity that an isolated body losses in a certain time period , either by contact with less humid air, or in the supports more or less idio-electric”.
Coulomb explained the laws of attraction and repulsion between electric charges and magnetic poles, although he did not find any relationship between the two phenomena. He thought that the attraction and repulsion were due to different kinds of fluids.
The SI unit of charge, the coulomb, and Coulomb's law are named after him.
External links
- French National Library The Mémoires of Coulomb available in pdf format.
- John J. O'Connor and Edmund F. Robertson. Charles-Augustin de Coulomb at the MacTutor archive
This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
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