Question

please explain lenzs law

Answer 1

The polarity of induced EMF is such that it tends to produce a current which opposes the change in magnetic flux that produced it.

Answer 2

As the north pole of the bar magnet moves towards the coil, the magnetic flux through the coil increases. Hence current is induced in the coil in such a direction that it opposes the increase in flux. This is possible only if the current in the coil is in a counter(anti)-clockwise direction with respect to an observer situated on the side of magnet.