Question

There was a demonstration I did our Zoom class with a falling magnet in a simple copper tube. Explain, in detail, the physics behind why the magnet slows its descent through the tube (it does not touch the sides). In your discussion be sure to explain why the magnet doesn't come to a stop in the tube and why it does not speed up. Your response should include at least 3 paragraphs to show your mastery of the material.

Answer 1

When a magnet is falling towards a copper tube , the magnetic flux keeps on increasing through the copper tube , according to lenz law an EMF will be induced in the copper tube which would oppose the cause of change of magnetic flux through the surface of copper tube. Thus , EMF will be induced which would repel the incoming magnet and this is the reason that the falling magnet doesn't speed up but slowly comes near to the surface of copper tube.

Now , the magnet doesn't stop in the copper tube because it's inertia overshoots the repulsion from the tube and also the gravity pulls the magnet downwards.

Now, when the magnet has started to fall below the tube, then the magnetic flux through the tube will begin to decrease and hence an EMF will be induced which opposes this change in the flux and hence an EMF will be induced which would attract the magnet towards itself (in upwards direction) but at the same time the gravity is pulling the magnet downwards , hence the magnet slowly falls downwards .

Please ask your doubts or queries in the comment section below.

Please kindly upvote if you are satisfied with the solution.

Thank you.