State Lenz's law. Explain by giving examples that Lenz's law is a consequence of conservation law of energy.

Explanation

According to Lenz.s law, the direction of the induced current in a closed circuit is such so as to oppose the change in magnetic flux, that produces it.
Lenz.s law is a consequence of the law of conservation of energy. To show it, let us consider a bar magnet pushed towards a conducting loop. When N-pole moves towards the loop, the face of the loop facing the north pole develops north polarity as per Lenz.s law so as to oppose the motion of magnet. Again, when N-pole moves away from the loop, the nearby face develops south polarity, thus opposing the motion of magnet away from the loop. It means that motion of magnet is automatically opposed every time. Hence, some work is to be done on the magnet to move it towards or away from the loop and this mechanical work is transformed into electrical energy. Thus, conservation law of energy is strictly followed.