Faraday’s laws of electromagnetic induction:
First law: When a conductor cuts or is cut by the magnetic flux, an EMF is induced in the conductor.
Second law: The magnitude of EMF induced in the conductor depends on rate of change of flux linking with the conductor or rate of cutting the flux by the conductor.
A stationary coil is placed near a movable permanent magnet and galvanometer is connected across the coil to measure current flowing through it.
As magnet is moved closer to or away from the coil, the galvanometer starts showing deflection. The magnitude of the current through the coil is zero when both coil & magnet are stationary and direction of coil current depends on the direction of movement of the magnet.
The expression of induced e.m.f. is as follows:
|e| α (change in flux)/(time in which it occurs) e = N (dФ /dt) volts
When the movement of magnet is slow, the flux linking the coil changes slowly and lower emf is induced which results in lower current as shown by the galvanometer.
When the movement of magnet is fast, the flux linking the coil changes at faster rate and high emf is induced which results in higher current as shown