inductance of a coil

In 1820, Oersted discovered the magnetic effect of electric current, according to which an electric current produces a magnetic field. The converse effect was discovered and demonstrated by Michael Faraday in UK and by Joseph Henry in USA in the year 1831. They showed that electric current can be produced in a coil of wire with the help of a magnetic field. The phenomenon is known as electromagnetic induction. Many vital devices like generators and transformers work on the principle of electromagnetic induction. The laws of physics governing the phenomenon of electromagnetic induction are known as Faraday's law of electromagnetic induction. The discovery of the phenomenon of electromagnetic induction lent support to the belief of physicists that 'symmetry is beauty in physics'.