Question

When a bar magnet with north pole pointing downward is dropped through a circular coil, and viewed from the top, the induce current in coil is ?

• A. Clockwise at all times
• B. Anticlockwise at all times
• C. First clockwise then anticlockwise
• D. First anticlockwise then clockwise

Answer 1

The correct option is D First anticlockwise then clockwise

As the magnet fall towards the loop, the loop will try to stop the magnet and so will develop a north pole on the top side of the loop. In order to do so the magnetic field lines will have to pass from under the loop towards the top and to do that the current will have to flow in the anticlockwise direction.

After crossing the loop, the polarity of the loop will change as now the south pole is moving away from the coil so the coil will develop north pole on the bottom side to attract the south pole of the magnet and stop its falling.

$\therefore$The current will be anticlockwise when the magnet is above the loop and clockwise when the magnet is below the loop. Hence option 'D' is the correct answer.