How it began
Michael Faraday worked in a laboratory in the basement of the Royal Institution in London. In August 1831 he made a ring-coil apparatus there, which the Royal Institution describes as the first electric transformer. He then began a long series of experiments in which he discovered electromagnetic induction. On 28 October 1831 he recorded in his laboratory diary that he was making many experiments with the great magnet of the Royal Society.
How it works
Faraday's breakthrough came when he wrapped two insulated coils of wire around an iron ring. When he passed a current through one coil, a momentary current was induced in the other coil. The same principle, in which a magnet, a coil and motion together produce electricity, underlies the generator he made in the same year.
What changed first
The discovery gave Faraday both a transformer and a generator in 1831, and it joined his other foundational findings in electromagnetism and electrochemistry, such as the laws of electrolysis and diamagnetism. Practical use was slow. The Royal Institution notes that although Faraday invented the generator in 1831, it took nearly 50 years before all the technology, including Joseph Swan's incandescent filament light bulbs, came into common use.
Where it stands today
The room where Faraday worked was preserved after his death in 1867 and later became part of the Faraday Museum at the Royal Institution. Visitors can see apparatus he used, including his electric motor, his generator and a giant electromagnet. The unit of capacitance, the farad, is named after him.
