Law of Induction

Faraday's Laws

First Law states:
Whenever the magnetic flux linked with a circuit changes, an
EMF is always induced in it. Whenever a conductor cuts magnetic
flux, an EMF is induced in that conductor.

Second Law states:
The magnitude of the induced EMF is equal to the rate of change
of flux-linkages.

Explanation. Suppose a coil has N turns and flux through it
changes from an initial value of 1 φ webers to the final value of 2 φ ,
webers in time t seconds. Then remembering that by flux-linkages
is meant the product of number of turns by the flux linked with the
coil, we have the following relation:

Initial flux linkages = 1φ N . And final flux linkages = 2 φ N
Then the induced EMF is

Usually a minus sign is given to the right-hand side expression to
signify the fact that the induced EMF sets up current in such a
direction that magnetic effect produced by it opposes the very cause
producing it.

Source ( pdf )
http://faculty.ksu.edu.sa/eltamaly/Documents/Courses/EE%20339/

MAGNETIC%20CIRCUITS.pdf