## Electromagnetic Induction

In 1831, Faraday made an important breakthrough by discovering how a moving magnet ran be used to generate electric currents. The phenomenon of inducing current in a coil by a changing magnetic field is called electromagnetic induction. The magnetic field be changed when there is a relative motion between the coil and the magnet.

Galvanometer: It is an instrument that can detect the presence of current in a circuit. The pointer remains at zero (centre of the scale) if no current flows through it and deflects to either the left or right of the zero mark depending on the direction of current.

## Explanation of Electromagnetic Induction

A current is induced in the secondary coil whenever the current in the primary coil is changing because the magnetic field associated with the primary coil changes. The induced current is found to be the highest ‘when the direction of motion of the coil is at right angles to the magnetic field.

## Fleming’s Right Hand Rule

The direction of Induced current is given by Fleming’s Right Hand Rule. Hold the forefinger, the central finger and the thumb of the right hand perpendicular to each other so that the forefinger indicates the direction of the field, and the thumb is in the direction of motion of the conductor. Then, the central finger shows the direction of current induced in the conductor.

Example 1.
A coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is (A) pushed into the coil, (B) withdrawn from inside the coil, (C) held stationary inside the coil?