Electromagnetic induction process was made by Michael Faraday In 1831. It is a method of obtaining an electric current with the aid of magnetic flux. he wound two coils on an iron ring and found that when switch was closed a deflection was obtained on a galvanometer. And when the switch was opened galvanometer was deflected in the reverse direction.
A similar deflection of galvanometer was found by moving a permanent magnet towards and away from a coil.
Thus he concluded that an electric current could be produced by the movement of magnetic flux relative to a coil. The magnitude of the induced e.m.f. is proportional to the rate at which the magnetic flux passing through the coil is varied.
Alternatively, we can say that when a conductor cuts or is cut by magnetic flux, an e.m.f. is generated in the conductor. The magnitude of this generated e.m.f. is proportional to the rate at which the conductor cuts or is cut by the magnetic flux.
First Law of Faraday's Electromagnetic Induction state that whenever a conductor are placed in a varying magnetic field emf are induced which is called induced emf, if the conductor circuit are closed current are also induced which is called induced current.
Whenever a conductor is rotated in magnetic field emf is induced which are induced emf.
Second Law of Faraday's Electromagnetic Induction state that the induced emf is equal to the rate of change of flux linkages (flux linkages is the product of turns, n of the coil and the flux associated with it).
FARADAY'S LAW'S EXPLANATION
Initial flux linkages = Nφ1
Final flux linkages = Nφ2
Change in flux linkages= Nφ2 – Nφ1
If (φ2-φ1) = φ
Then change in flux linkages = Nφ
Rate of change of flux linkages = Nφ/t wb/sec
Taking derivative of right hand side we get
Rate of change of flux linkages = Ndφ/dt wb/sec
Rut according to Faraday's laws of electromagnetic induction, the rate of change of flux linkages equal to the induced emf, hence we can write
= Ndφ/dt volt
Generally Faraday's laws is written as
e = -Ndφ/dt volt
Where negative sign represents the direction of the induced current in the conductor will be such that the magnetic field produced by it will oppose the verb cause produce it.