Saturday, June 14, 2014

Charles Augustin de Coulomb and the Electrostatic Force

Charles Augustin de Coulomb
(1736 – 1806)
Portrait by Hippolyte Lecomte
On June 14, 1736, French physicist Charles Augustin de Coulomb was born. He is best known for developing Coulomb's law, the definition of the electrostatic force of attraction and repulsion, but also did important work on friction. The SI unit of electric charge, the coulomb, was named after him.

Charles Augustin de Coulomb received a good education in mathematics, astronomy, chemistry and botany since both sides of his family were respected and quite wealthy which allowed Coulomb to be raised as a child of privilege. He went to school in the Collège Mazarin in Paris, but, after his father had made some poor decisions, the family faced financial difficulties and Coulomb moved along with his father to Montpelier, where he joined the Academy of Sciences and managed to present several papers, focusing mostly on topics in astronomy and mathematics. However, in 1760, Coulomb started his formal studies in Paris, completing them less than two years later and embarking on a long career within the Military Engineering Corps. His duties forced him to make several moves over the subsequent decades and during a longer stay in the West Indies, his health issued started to increase. He never fully recovered, even following his return to France in the early 1770s.

Coloumb began to focus more and more in engineering and mechanics, which provided him with a firm foundation on which his later theoretical efforts were built. He submitted his first treatise to the Academy of Sciences in Paris in 1773, and many more would follow on topics ranging from mathematical solutions of engineering problems to studies of friction, elasticity, electricity and magnetism. About four years later, the scientist discussed the magnetic compass including a description of his torsion balance, which increased his reputation significantly. After a visit to Rochefort in the late 1770s, Coloumb was promoted to a Captain and employed at La Rochelle, the Isle of Aix and Cherbourg. In this period, Coulomb discussed his experiments with electrostatic forces and explained the inverse square law that they led Coulomb to posit. Similar to Isaac Newton’s inverse square law of gravitational force, Coulomb’s law states that the electric force between charged objects inversely depends upon the distance between the objects. That is, like gravity, the electric force acts in a line between two objects and decreases with the square of the distance between them. The primary difference between the law for gravity and that for electric force is that gravitation is influenced by the mass of the objects, whereas Coulomb’s law depends upon the charge of the objects involved. When the objects in question are both positively or both negatively charged, the forces between them are repulsive, but attractive forces arise between objects carrying opposing charges [1].

When the French Revolution started, Coulomb 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 and later became one of the first members of the French National Institute. Charles-Augustin de Coulomb passed away on August 23, 1806.

At yovisto, you may be interested in an introduction to Coulomb's Law and Electric Fields.



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