With the help of an activity, explain the method of inducing an electric current in a coil with a moving magnet. Mention one practical application of electromagnetic induction.

Explanation

Activity to demonstrate the method of inducing electric current in a coil with a moving magnet :
1] Wind a coil of an insulated copper wire having a large number of turns on a cardboard cylinder .
2] Connect the ends of the coil to a galvanometer.
3] Take a strong bar magnet and move its north pole towards one end of the coil. Check the deflection in the galvanometer.
4] Hold the magnet inside the coil for some time and check for any deflection.
5] Move the magnet away from the coil and observe the deflection in the galvanometer.
Inference : Whenever magnet is moved, the magnetic field is changed. This induces a potential difference causing current to flow through the circuit which is indicated by deflection of the galvanometer needle . Change in direction of motion of the magnet cause deflection in the opposite direction indicating that the direction of current in the circuit is reversed. If both coil and magnet are stationary, there is no change in magnetic field . Hence no deflection is observed in the galvanometer and hence no current is induced.
Electric generator is one practical application of electromagnetic induction.