In 1831, Michael Faraday, an English physicist gave one of the most basic laws of electromagnetism called Faraday's law of electromagnetic induction. This law explains the working principle of most of the electrical motors, generators, electrical transformers and inductors. This law shows the relationship between the electric circuit and magnetic field. Faraday performed an experiment with a magnet and coil. During this experiment, he found how emf is induced in the coil when flux linked with it changes.
In this experiment, Faraday takes a magnet and a coil and connects a galvanometer across the coil. At starting, the magnet is at rest, so there is no deflection in the galvanometer i.e needle of the galvanometer is at the center or zero position. When the magnet is moved towards the coil, the needle of galvanometer deflects in one direction. When the magnet is held stationary at that position, the needle of galvanometer returns back to zero position. Now when the magnet is moved away from the coil, there is some deflection in the needle but in opposite direction and again when the magnet becomes stationary, at that point with respect to the coil, the needle of the galvanometer returns back to the zero position. Similarly, if the magnet is held stationary and the coil is moved away and towards the magnet, the galvanometer shows deflection in a similar manner. It is also seen that the faster the change in the magnetic field, the greater will be the induced emf or voltage in the coil. Position of magnetDeflection in galvanometerMagnet at restNo deflection in galvanometerMagnet moves towards the coilDeflection in galvanometer in one directionMagnet is held stationary at same position (near the coil)No deflection in galvanometerMagnet moves away from the coilDeflection in galvanometer but in opposite directionMagnet is held stationary at same position (away from the coil)No deflection in galvanometer