Question

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) becomes an alternating current once the permanent magnet stops moving and the pot’s magnetic poles then flip back and forth rapidly. d) stops flowing

Answer 1

the correct one is d

Step-by-step explanation:

Let's analyze the situation before reviewing the answers.

When the magnet moves towards the pot, an electromotive force is induced by Faraday's law

fem =
`- (d \Phi_B )/(dt)` - dfi / dt

`\Phi_B` = B . A

In the pot, because it is metallic, a current is created and it is in the opposite direction to the variation of magnetic flux.

By stopping the magnet the flux becomes constant and therefore its derivative is zero, therefore there is no electromotive force and consequently no current.

When reviewing the answers, the correct one is d