Question

A bar magnet is moved along the axis of a copper ring placed far away from the magnet. Looking from the side of the magnet, an anti-clockwise current is found to be induced in the ring. Which of the following may be true?

• A. The south pole faces the ring and the magnet moves towards it.
• B. The north pole faces the ring and the magnet moves towards it.
• C. The south pole faces the ring and the magnet moves away from it.
• D. The north pole faces the ring and the magnet moves away from it.

Answer 1

Answer: (B), (C)

The correct options are
B The south pole faces the ring and the magnet moves away from it.
C The north pole faces the ring and the magnet moves towards it.

When magnet is moving towards the ring, as the current flows in anti-clockwise direction when seen from magnet, a magnetic field directed towards the magnet from the ring is observed.
By Lenz's law this field is to oppose the movement of the magnet towards the ring.
Therefore the N-pole should be facing the ring, as only then will the induced field by the ring will oppose the movement of the approaching magnet.
Therefore, the north pole faces the ring and the magnet moves towards it and the south pole faces the ring and the magnet moves away from it.