Heinrich Lenz began his academic life as a student of geophysics at the University of Dorpat (now part of Russia). His first teaching post was at the St. Petersburg Academy, where he showed in 1834, that the direction of a current induced by an electromagnetic force always opposes the electromagnetic force that produces it (Lenz's law). This law later helped Hermann Helmholtz develop the law of conservation of energy, of which Lenz's law and Joule's law (independently discovered by Lenz) were special cases.
Copyright 1997, The Open University