Electromagnetic Induction

What is Electromagnetic Induction?

Electromagnetic induction is the production of voltage in a conductor when there is relative motion between the conductor and a magnetic field.

This phenomenon can be demonstrated by an experiment as discussed below:

• Wind an insulated copper wire on a paper, cardboard or wooden cylinder in order to form a coil in the form of a solenoid.

• Connect the two ends of the solenoid to a galvanometer, then move a magnet horizontally towards the end of coil.

• The reading of the galvanometer is zero (0) when the magnet is stationary.

• If the North pole of the strong magnet is moved towards the coil, the galvanometer deflects for a short time to the right. The deflection shows that there is induced current or voltage in the coil.

• If the magnet stops moving, the current stops flowing. This shows that as long as the magnet keeps moving current flows in the solenoid.

• If the magnet is moved away from the solenoid, current flows in the opposite direction, and the galvanometer deflects to the left.

• When the magnet is stationary in the solenoid, no deflection takes place.

We see that the direction of the current produced in the coil depends on whether the magnet is moved toward or away from the coil, but in either case, a current is produced.