Coulomb, who by using very long and thin magnets, so arranged that the action of their distant poles was negligible, succeeded in establishing the law, which has since been confirmed by more accurate methods, that the force of attraction or repulsion exerted between two magnetic poles varies inversely as the square of the distance between them.
No material advance upon the knowledge recorded in Gilbert's book was made until the establishment by Coulomb in 1785 of the law of magnetic action.
Coulomb, 2 however, by using long and thin steel rods, symmetrically magnetized, and so arranged that disturbing influences became negligibly small, was enabled to deduce from his experiments with reasonable certainty the law that the force of attraction or repulsion between two poles varies inversely as the square of the distance between them.
The accuracy of this law was in 1832 confirmed by Gauss, 3 who employed an indirect but more perfect method than that of Coulomb, and also, as Maxwell remarks, 1 The quotations are from the translation published by the Gilbert Club, London, 1900.
The friction of water, investigated for slow speeds by Coulomb, was measured for higher speeds by William Froude (1810-1879), whose work is of great value in the theory of ship resistance (Brit.
CHARLES AUGUSTIN COULOMB (1736-1806), French natural philosopher, was born at Angouleme on the 14th of June 1736.
Coulomb is distinguished in the history alike of mechanics and of electricity and magnetism.
The practical unit of quantity of electricity, the coulomb, is named after him.
Coulomb proved that this mechanical force varies inversely as the square of the distance between the centres of the spheres.
Coulomb proved experimentally that the electric force just outside a conductor at any point is proportional to the electric density at that point.
Coulomb proved the proportionality of electric surface force to density, but the above numerical relation E= 42ra was first established by Poisson.
Hence if we remove the charge -q at B and distribute electricity over the surface PO with a surface density a, according to the Coulomb-Poisson law, a = qAO/21rAP3, the field of force to the left of PD will fulfil the required boundary conditions, and hence will be the law of distribution of the induced electricity in the case of the actual plate.
Meters intended to measure electric quantity are called coulomb meters and also ampere-hour meters; they are employed for the measurement of public electric supply on the assumption that the electromotive force or pressure is constant.
Experiments on friction have been made by Coulomb, Samuel Vince, John Rennie, James Wood, D.
The following empirical formulae for the stiffness of hempen ropes have been deduced by Mono from the experiments of Coulomb: Let F be the stiffness in pounds avoirdupois; d the diameter of the rope In inches, fl = 48d2 for white ropes and 35d2 for tarred ropes; r the effectire radius of the pulley in inches; T the tension in pounds.
Coulomb (1736-1806), who in France addressed himself to the same kind of exact quantitative work as Cavendish in England.
Coulomb has made his name for ever famous by his invention and application of his torsion balance to the experimental verification of the fundamental law of electric attraction, in which, however, he was anticipated by Cavendish, namely, that the force of attraction between two small electrified spherical bodies varies as the product of their charges and inversely as the square of the distance of their centres.
Adopting the hypothesis of two fluids, Coulomb investigated experimentally and theoretically the distribution of electricity on the surface of bodies by means of his proof plane.
The French mathematicians, Coulomb, Biot, Poisson and Ampere, had been content to accept the fact that electric charges or currents in conductors could exert forces on other charges or conductors at a distance without inquiring into the means by which this action at a distance was produced.
Coulomb experimentally proved that the law of attraction and repulsion of simple electrified bodies was that the force between them varied inversely as the square of the distance and thus gave mathematical definiteness to the two-fluid hypothesis.