Electro-Magnetic Induction

Electro-Magnetic Induction

Electromagnetic induction is process by which when a conductor (which form a closed circuit) is placed in a changing magnetic field, an e.m.f is induced in that conductor by electro-magnetic induction.

Let have a coil having large number of turns to which a galvanometer is connected. This coil is placed near to a permanent bar magnet. When this bar magnet is takes near to the coil or away from the coil, an e.m.f is induced in the circuit. Due to e.m.f induction needle of galvanometer start deflecting and result to induction of voltage and current in the coil.

On the other hand, when Bar Magnet is kept at one place and coil having large number of turn takes near and away from the bar magnet, then also needle of galvanometer start deflecting and result to induction of voltage and current in the coil. The deflection of the needle is opposite in the two case.

But if the bar magnet and coil kept stationary, no matter how much the flux link to the coil, no e.m.f will be induced in the coil and no deflection will be occur in galvanometer.

The following points are worth to note from above discussion that

1.    The deflection of the galvanometer needles show that e.m.f is induced in the coil when coil is move near or away from the bar magnet or when bar magnet is move near or away from the coil.

2.     The direction of induced e.m.f in the coil depends upon the direction of magnetic field and direction of the motion of coil.