Main Entry: hen·ry

Pronunciation: \ˈhen-rē\

Function: noun

Inflected Form(s): plural henrys or henries

: the practical mks unit of inductance equal to the self-inductance of a circuit or the mutual inductance of two circuits in which the variation of one ampere per second results in an induced electromotive force of one volt

Henry, Joseph (1797–1878), American physicist. Henry was a schoolteacher in Albany, New York, and later a professor of mathematics and natural philosophy at Princeton. He conducted a series of investigations into electric phenomena, particularly those related to magnetism. His first major achievement was building a powerful electromagnet, for which he developed insulated wire in order to make a closely wound coil of several layers. He is also credited with constructing primitive versions of the telegraph and the electric motor. In 1846 he became the first secretary and director of the Smithsonian Institution in Washington, D.C. In recognition of his work, his name was given to the henry, the unit of electrical inductance, by international agreement in 1893.