If you move the north pole of a permanent magnet toward the surface of an aluminum pot, a current will flow through that pot and the pot will become magnetic-repelling your permanent magnet. If you stop the permanent magnet just before it touches the pot and then hold the permanent magnet stationary, the repulsive force between the pot and the permanent magnet will gradually disappear. The repulsive force disappears because the electric current in the pot
A) becomes non-magnetic once the permanent magnet stops moving.
B) stops increasing and becomes steady once the permanent magnet stops moving.
C) gradually slows to a stop once the permanent magnet stops moving.
D) becomes an alternating current once the permanent magnet stops moving and the pot's magnetic poles then flip back and forth rapidly.

Question

Quizplus · Accepted Answer

The repulsive force disappears because the electric current in the pot, which is induced by the movement of the magnet, gradually slows to a stop once the permanent magnet stops moving. This is due to Lenz's law, which states that the direction of the induced current will be such that it opposes the change in magnetic flux that produced it. When the magnet stops moving, there's no change in magnetic flux to maintain the induced current, so the current and the resulting magnetic field it creates gradually disappear.

If You Move the North Pole of a Permanent Magnet