The first widely accepted operating generator was invented by Michael Faraday. In 1831, Faraday discovered electromagnetic induction, the principle behind the electric transformer and generator. This discovery was crucial in allowing electricity to be transformed from a curiosity into a powerful new technology. During the remainder of the decade he worked on developing his ideas about electricity. He was partly responsible for coining many familiar words including 'electrode', 'cathode' and 'ion’. He gave his name to the 'farad', originally describing a unit of electrical charge but later a unit of electrical capacitance. In addition to all this he realized that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. This was later known as Faraday’s Law.