OK, science geeks; gather 'round. Got a little quiz for ya. (LDRS PRIZE INCLUDED)

https://www.iflscience.com/physics/what-happens-when-you-drop-magnet-through-copper-tube

We're probably all familiar with this classic, right? The old "magnet down a copper tube" demonstration. Very cool and intuitive way to show the back and forth interaction of electrical and magnetic fields.

But let's change one thing and see what happens. What if the copper was in the form of a sphere instead? A hollow sphere with the magnet inside. (never mind how you would actually CONSTRUCT such a thing, just assume we figured out a way)

Would the magnet be forever suspended dead center inside the sphere? Would it eventually settle to a motionless state, or would it constantly be oscillating about the spheres' center point (seeking center / overshooting / seeking again)? Or would it simply fall to the bottom?

What do you think? To make it interesting, the most plausible and/or entertaining answer (as decided solely by me) will get a free lunch from the onsite vendor of your choice at LDRS. Of course you have to attend LDRS to win this awesome prize, but even if you're not going I'd love to hear what you think.

Let's have fun, and remember, show your work! :wink:

The magnet would fall to the bottom, maybe a little slower than gravity. The field interaction cause drag (repulsive force) that it proportional to the differential velocity between the magnet and copper. With no velocity there is no force so the magnet will call under gravity reaching a terminal velocity determined by the drag force until it reached the bottom.

Ravenex said:

The magnet would fall to the bottom, maybe a little slower than gravity. The field interaction cause drag (repulsive force) that it proportional to the differential velocity between the magnet and copper. With no velocity there is no force so the magnet will call under gravity reaching a terminal velocity determined by the drag force until it reached the bottom.

Click to expand...

show your work!

The magnet will simply fall to the bottom of the sphere as there is no opposing permanent magnetic field to suspend it.

Bob

You're all wrong! Copper thieves will steal the sphere and exchange it for drug money at the nearest recycling facility. If confronted about the magnet they will claim it was that way when they found it.

GRIFFIN said:

show your work!

Click to expand...

tmacklin said:

You're all wrong! Copper thieves will steal the sphere and exchange it for drug money at the nearest recycling facility. If confronted about the magnet they will claim it was that way when they found it.

Click to expand...

What he said.

For the electro/magnetic effect to work there needs to be motion between the copper and the magnet.
Notice in the video the OP posted how the magnet is given a spin.

So first you need to create the copper sphere with the magnet inside. Then you need to get one moving with respect to the other. Getting the magnet to start spinning within the sphere would be problematic. Perhaps you could try spinning the sphere but you would want the magnet to initially be suspended and not just sitting on the bottom.

I would think with a fast enough spin you possibly could create enough force to suspend the magnet - until the air in the sphere got the magnet spinning as well which would reduce the effect (if the magnet spins with the copper shell than you lose your magnetic field with respect to the copper). Or if you are spinning the magnet and the sphere is stationary than the magnet will slow down due to air friction

So now you need to get the magnet somehow into a sphere, initially suspend it until you get it or the sphere rotating, and to keep the spin going (with respect to the magnet) you will need a vacuum inside the sphere. Constructing this is getting more difficult...

I would also think this would only work along the axis, so if the magnet drifts to the side it could make contact with the sphere and start bouncing around inside.

Long run - best option is to sell the copper and use the money to buy more rocket stuff