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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]

#81

Post by fnordfnordfnord »

IgorPartola wrote: post #66
rbanffy wrote: post #43

Earlier quoted context omitted.

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...

I forget what type we used but it was cooled by liquid nitrogen. That prof. used lots of magnets and superconductors in his research, some cooled by Helium-3. Now that stuff is expensive .

The high-temperature ones were probably Yttrium-Barium-Copper-Oxides (YBCO) I've seen this demo done with them. The magnet's motion is almost undetectable, they appear suspended in the copper pipe until they start to warm up.

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

#82

Post by aunty_helen »

dublinben wrote: post #40

Original link: https://www.youtube.com/watch?v=keMpUaoA3Tg This digg page is blogspam.

The problem with the youtube link however is that any video with 'magnet' in the title brings you uncomfortably close to thousands of youtube nutters posting about perpetual motion machines.

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

#83

Post by omegaham »

556790 wrote: post #80

I wonder, with a tube that is of sufficient thickness and a magnet of sufficient strength, would it be possible to levitate the magnet inside the tube?

The best way to do it is with a superconducting magnet.

And no, it doesn't quite levitate, but it takes a very long time for it to fall through. I think the video we watched in high school physics class had it take about fifteen seconds to go an inch and a half.

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

#84

Post by sbilstein »

Crito wrote: post #35
sillysaurus2 wrote: post #32

Earlier quoted context omitted.

Could this be used as a kind of elevator tech? I'd love to ride one of these down a gigantic copper tube. It'd be completely impractical, of course, but a whole lot of fun.

You could probably use eddy-current brakes as a safety system for elevators. Many roller coasters use eddy-current brakes. It would take a hell of a lot of magnets to strap to a person to allow them to jump down a copper pipe though.

Yea my hs physics teacher demoed this and talked to us about possible applications for a while. i don't remember any but thank you wikipedia: http://en.wikipedia.org/wiki/Eddy_current#Applications

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

#85

Post by reddog9287 »

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…

Yeah I'm actually pretty surprised that this made it to the front page. Pretty novel and I thought more people would know about it (being a typical physics class demonstration). Cool nonetheless.

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

#87

Post by JackFr »

whatshisface wrote: post #36
sillysaurus2 wrote: post #32

Earlier quoted context omitted.

Could this be used as a kind of elevator tech? I'd love to ride one of these down a gigantic copper tube. It'd be completely impractical, of course, but a whole lot of fun.

The inverse square law of force strength falloff would make it very hard to scale this linearly, that combined with the fact that weight increases with the cube of size means that the magnets involved would have to be incredibly strong. Not impossibly strong mind you, if magnets can hold a hundred ton train car off the ground I am sure they could slow the fall of an elevator. I'd not want to be inside that elevator w…

Every elevator you've been in has been held up by a magnet. They're just not obvious inside the motor housing.

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

#89

Post by lotharbot »

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...

http://search.dilbert.com/comic/We%20Didn%27t%20Have%20Zeros (Sept 8, 1992 Dilbert)

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

#90

Post by throw_away »

JackFr wrote: post #87
whatshisface wrote: post #36

Earlier quoted context omitted.

The inverse square law of force strength falloff would make it very hard to scale this linearly, that combined with the fact that weight increases with the cube of size means that the magnets involved would have to be incredibly strong. Not impossibly strong mind you, if magnets can hold a hundred ton train car off the ground I am sure they could slow the fall of an elevator. I'd not want to be inside that elevator w…

Every elevator you've been in has been held up by a magnet. They're just not obvious inside the motor housing.

To be pedantic, they're usually held up by a counterweight or by hydraulics. They generally move by magnets, though.
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