Electrical Engineering ⇒ Topic : Faradays Laws of Electromagnetic Induction

Faraday's Laws of Electromagnetic Induction

Faraday performed a series of experiments to demonstrate the phenomenon of electromagnetic induction. He summed up his conclusions into two laws, known as Faraday's laws of electromagnetic induction.

First Law. It tells us about the condition under which an e.m.f. is induced in a conductor or coil and may be stated as under

When the magnetic flux linking a conductor or coil changes, an e.m.f is induced in it.

It does not matter how the change in magnetic flux is brought about. The essence of the first law is that the induced e.m.f. appears in a circuit subjected to a changing magnetic field.

Second Law. It gives the magnitude of the induced e.m.f. in a conductor or coil and may be stated as under

The magnitude of the e.m.f induced in a conductor or coil is directly proportional to the rate of change of flux linkages i.e

The direction of induced e.m.f. (and hence of induced current if the circuit is closed) is given by Lenz's law. The magnitude and direction of induced e.m.f. should be written as

The minus sign on the R.H.S. represents Lenz's law mathematically. In SI units, e is measured in volts, (Φ) in webers and t in seconds.