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What Happens When You Drop A Magnet Inside A Copper Tube [video]

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Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#41

Post by Shish2k »

tedsanders wrote: post #25
TrainedMonkey wrote: post #19

If magnet was not rotated when dropped through the tube, would it simply stick to one wall in case of slightest imbalance?

No. Because copper isn't ferromagnetic, it will not be magnetized by the magnet, and consequently the magnet and the copper will not be attracted to each other. (In fact copper is diamagnetic, so it will actually slightly repel.) Source: I am a magnet scientist.

> I am a magnet scientist.

Judging entirely by the name, that sounds awesome :D What do you do all day?

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#42

Post by dfbrown »

martinvol wrote: post #24
TrainedMonkey wrote: post #19

If magnet was not rotated when dropped through the tube, would it simply stick to one wall in case of slightest imbalance?

I can't clearly remember my psychics class, But I think I'd fall a bit faster, as the movement through the pipe is considerable as well.

I don't think the spinning should have any effect on the speed. Only the vertical movement would create eddy currents. It could be he does it to keep the magnet stable as it falls (like spin on a football).

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#43

Post by rbanffy »

IgorPartola wrote: post #30
taliesinb wrote: post #20

Earlier quoted context omitted.

You can also think of it as magnetic flux lines encountering "drag" as they pass through conductors. The limiting behavior of this view is in type II superconductors, which entirely "pin" flux lines -- they present an effectively infinite resistance to the movement of flux lines. That's why a magnet levitates over such a superconductor. [1] You can even image these "vortices" directly [2] [1] http://en.wikipedia.org/…

The levitation over a superconductor was the other cool demo that the professor did :).

Lucky kids. When I was in school, the only commercial superconductors were liquid Helium cooled Niobium-Titanium alloys, something not many classrooms could handle. ;-)

Luckily, when I got to programming, we already had zeroes and ones. Imagine our predecessors who had to do it with uppercase o's and lowercase l's...

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#46

Post by orblivion »

IgorPartola wrote: post #2

Yup, it's pretty cool. This was one of the most impressive demo's my physics professor did in our freshman physics class. The point is that as the magnet is falling through the copper tube it creates an electric current which then creates a magnetic field in the opposite direction of the magnet's movement. In other words, this is the practical application of the Right Hand Rule [1]. Two fun facts about it: first, if…

Wait so does that mean that, ironically, friction is what it allows magnets to fall through a tube that isn't superconducting?

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#48

Post by malandrew »

adsr wrote: post #27
malandrew wrote: post #8

I can only begin to imagine how much a piece of copper tubing that thick costs. That's a lot of copper.

A kg is about $7 at the moment it seems, so suppose that's 5 kg then $35.

That's it? I was under the impression that copper was far more expensive and is the reason why expresso machines are as expensive as they are.

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#49

Post by bjornsing »

orblivion wrote: post #46
IgorPartola wrote: post #2

Yup, it's pretty cool. This was one of the most impressive demo's my physics professor did in our freshman physics class. The point is that as the magnet is falling through the copper tube it creates an electric current which then creates a magnetic field in the opposite direction of the magnet's movement. In other words, this is the practical application of the Right Hand Rule [1]. Two fun facts about it: first, if…

Wait so does that mean that, ironically, friction is what it allows magnets to fall through a tube that isn't superconducting?

Yes, pretty much, but you usually call it electrical resistance.

Re: What Happens When You Drop A Magnet Inside A Copper Tube [video]

#50

Post by dllthomas »

rbanffy wrote: post #43
IgorPartola wrote: post #30

Earlier quoted context omitted.

The levitation over a superconductor was the other cool demo that the professor did :).

Lucky kids. When I was in school, the only commercial superconductors were liquid Helium cooled Niobium-Titanium alloys, something not many classrooms could handle. ;-) Luckily, when I got to programming, we already had zeroes and ones. Imagine our predecessors who had to do it with uppercase o's and lowercase l's...

lOl
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