Electromagnetic Induction -
For a long time electricity and magnetism were treated as separate entities. It was established only in the early nineteenth century that electric and magnetic fields are different aspects of the same phenomenon. It was experimentally proved that electric charges in motion produce magnetic fields. In this regard, we can recall the experiment conducted by Oersted in which an electric current set up in a conductor deflects a magnetic compass needle placed in its vicinity.
The converse of this effect was also proved to be true by the experiments of Michael Faraday and Joseph Henry. They experimentally demonstrated that electric currents were induced in closed coils when a changing magnetic field is applied to them. This phenomenon is called electromagnetic induction.
The working of generators and transformers is based on the phenomenon of electromagnetic induction.