21. A metal ring is held horizontally and bar magnet is dropped through the ring with its length along the axis of the ring. The acceleration of the falling magnet is (1996)
Solution:
As the magnet falls, magnetic flux linked with the ring increases.
By Lenz's law, an induced current is set up in the ring which opposes the downward motion of the magnet.
An upward repulsive magnetic force acts on the magnet, resulting in an acceleration $a < g$.
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