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Quick Answer. Michael Faraday discovered the law of electromagnetic induction in 1831. He realized that current in a circuit can be induced by changing the magnetic field. Faraday tested it by wrapping a paper cylinder with a wire and connecting the coil to a galvanometer. Faraday then moved the magnet back and forth inside the cylinder.
Faraday's and AmpÃ¨re's work showed that a time-varying magnetic field acted as a source of an electric field, and a time-varying electric field was a source of a magnetic field. Thus, when either field is changing in time, then a field of the other is necessarily induced.