André Marie Ampère

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André-Marie Ampère

Library of Congress

[b. Lyon, France, January 20, 1775, d. Marseilles, France, June 10, 1836]

Ampère was the first to recognize that there is a direction for the flow of an electric current and to introduce a convention for determining that direction. He showed that wires carrying electric currents attract and repel each other magnetically. The amount of magnetism reflects the strength of the current. In 1827 he put his discoveries into the mathematical form known as Ampère's law: The magnetic force generated between two current-carrying wires varies directly with the product of their currents and inversely with the square of the distance between the wires. Ampère was one of the first to show that when current flows through a wire coiled into a helix, or three-dimensional spiral, the wire behaves like a bar magnet. This property later fueled many of the inventions of the age of electricity, including the telegraph, electric motor, and telephone.

Ampère, André-Marie (1775-1836). French physicist, founder of the science now known as electromagnetism. Ampère, a child prodigy in mathematics and later an inspired experimentalist, was the first to demonstrate, and to express mathematically, the relationship between electricity and magnetism. He initiated a standard system of measurement for electric currents. His works include an Essai sur la philosophie des sciences (1834-44) and the posthumously published Journal et correspondance.

[Malcolm Bowie]