Lenz’s Law of Electromagnetic induction
In 1835, Mr. Lenz had formulated that electromagnetically induced current flows in such direction that the action of magnetic field setup by it tends to oppose the cause which produce it.According to his name, this law is known as Lenz’s Law.
Now we describe the direction of induce current.
From the figure 1, It is seen that when N-pole of the bar magnet approaches the coil, the induced e.m.f is produced in the coil and this induce e.m.f set up the induced current which flows in the anti clockwise direction in the coil as seen from magnet side. This induced current produces a magnet field in the coil, and face of the coil becomes a N-pole, The result N-pole of the coil & N-pole of the bar magnet repel each other. A mechanical energy spent to overcome this repulsive force and this mechanical energy is converted into electrical energy in the coil.
And when the magnet is withdrawn from the coil as shown in fig-2, same induced current flows in the clockwise direction in the coil and this induced current makes the face of the coil a S-pole.
Therefore, N-pole of bar magnet & S-pole of coil attract each other. A mechanical energy is required to overcome this force of attraction and that mechanical energy is converted in to electrical energy.