Faraday's Law of Electromagnetic Induction

Electromagnetic Induction:

The phenomenon by which an emf is induced in a conductor when it is cut by magnetic flux is known as electro-magnetic induction.

Faraday’s First Law

It states that, When-ever a conductor cuts a magnetic field or vice-versa, an e.m.f. (electro-magnetic force) is induced in it and it sets up in such a direction so as to oppose the cause of it.

Faraday’s second law

It states that the magnitude of induced e.m.f. is equal to the rate of change of flux linkage.

Mathematically

e = -N dØ / dt

where   e= Induced emf
            N= Number of turns of coil
           dØ / dt = Rate of change of flux

the minus sign represents that the induced emf or current sets up in a direction so as to oppose the cause of it ( according to Lenz’s Law).

Lenz’s Law

Lenz’s law states that:

   "The direction of induced current is always such as to oppose the cause which produces it".
   That is why a –ive sign is used in Faraday’s law.