Faraday's law :
Changing the magnetic flux through a loop of wire induces a current. Faraday's law states that the emf induced in a wire is proportional to the rate of the flux through the loop. Mathematically,
where N is the number of loops, ΔΦ is the change of flux in time, Δ t. The minus sign indicates the polarity of the induced emf.The preceding equation is easy to use when the flux is set up by an electromagnet. If the electromagnet is turned on or off, the induced emf is equal to the number of turns in the loop times the rate of change of flux. The flux might also be changed through a loop altering the size of the loop. Imagine a slide wire, as shown in Figure 1 , where l is the length of the wire that moves in contact with the U-shaped wire. In this case, ε= Blv, where v is the velocity of the sliding length.
Note that this induced emf is indistinguishable from that of a battery and that the current is still just the rate of the motion of charges; therefore, Ohm's law and other relationships for currents in wires are still valid.Hope the above explanation was helpful.
