A bar magnet is freel falling along the axis of a circular loop as shown in Figure. State whether its acceleration a is equal to greater than or less than the acceleration due to gravity g.

Explanation

Acceleration of the bar magnet will be less than acceleration due to gravity `(altg)` because according to Lenz's law, whatever may be the direction of induced current, it will oppose the cause. Here, the cause is, the free fall of magnet and so that induced current will oppose it and acceleration due to gravity g.
Alternate method This can be understood in a different mannar. When the magnet falls downwards with its north pole dounwards. The magnetic field lines passing through the coil in the downward direction increase. Since, the induced current opposes this, the upper side of the coil will become north pole, so that field lines of coil's magnetic feild are upwards. Now, like poles repel each other. Hence, `altg`.

If this circular loop had a slot, an emf in that case will be induced but no current will flow i.e., a = g.