Question

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

• A. is equal to g
• B. is less than g
• C. is more than g
• D. depends on the diameter of ring and length of magnet

Answer 1

The correct option is B is less than g

Falling of the magnet into the metal ring increases the flux through the ring. According to Lenz Law, emf would be induced in the ring such that the induced magnetic flux opposes the increasing flux through the ring.

Thus a force acts on the magnet upwards when it is falling into the ring and its acceleration decreases and remains less than $g$.