Magnet Academy: Joseph Henry

Joseph Henry was an American scientist who pioneered the construction of strong, practical electromagnets and built one of the first electromagnetic motors. During his experiments with electromagnetism, Henry discovered the property of inductance in electrical circuits, which was first recognized at about the same time in England by Michael Faraday, who was the first to publish on the subject. In honor of Henry, the SI unit of inductance bears his name. One henry equals the inductance of a circuit with an induced voltage of one volt and an inducing current that changes one ampere per second.