When the key is released, the current in C2 and the
resulting magnetic field decreases from the maximum value to zero in a
short time This results in a decrease in magnetic flux through coil C1
and hence again induces an electric current in coil C1* The common
point in all these observations is that the time rate of change of magnetic
flux through a circuit induces emf in it Faraday stated experimental
observations in the form of a law called Faraday’s law of electromagnetic
induction