A bar magnet is released from rest along the axis of a very long vertical copper tube. After some time the magnet will:
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Question

A bar magnet is released from rest along the axis of a very long vertical copper tube. After some time the magnet will:

G1 Physics · Accepted Answer

As the magnet falls, the magnetic flux through the conducting copper tube changes. Eddy currents are induced in the tube. By Lenz's law, their magnetic effect opposes the motion of the falling magnet. At sufficiently large speed, the upward magnetic drag approximately balances the weight, so the magnet approaches a terminal speed. Hence it moves downward with almost constant speed. Option C follows.