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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]

#11

Post by salgernon »

IgorPartola wrote: post #5
baq wrote: post #4

be very careful when handling such powerful magnets - if you have something metalic on you, they might jump off the table and smack you really hard. bones will be broken.

Fingers will also be pinched and possibly broken.

The latch on our clothes dryer broke; the door would no longer snug up and maintain the seal or necessary pressure for the safety switch. I now have a 2x2x1" rare earth magnet holding the door shut against the dryer frame. Its strong enough to keep the door snug, but I can still open the dryer door with a good tug.

I'm not sure why I had a 2x2x1" neodymium magnet laying around, but I'm glad I did.

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

#12

Post by Loughla »

deletes wrote: post #10

Where can you buy something like that. A magnet is around 150$, but I have no idea where to get a copper tube of that thickness.

Not sure where to get one at that thickness or diameter, but a specialized plumbing supply company can get you most standard size and diameter of copper piping.

That one is huge, though. In theory, this should work with smaller, but powerful magnets, and thinner tubes, correct?

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

#13

Post by IgorPartola »

deletes wrote: post #10

Where can you buy something like that. A magnet is around 150$, but I have no idea where to get a copper tube of that thickness.

You really don't need anything as fancy. A small magnet and a narrow aluminum tube will do just fine. It won't be quite as impressive, but drop a pebble from the same height not through the tube and watch the delay for the magnet dropping. A four foot length of tube about 1/2 to 3/4 inch in diameter would do nicely.

Edit: try cast iron if you must have a big pipe. It's likely to be much cheaper. The thickness shouldn't make much of a difference either, so maybe even a cooking pot with a cut off bottom would work.

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

#14

Post by deletes »

Loughla wrote: post #12
deletes wrote: post #10

Where can you buy something like that. A magnet is around 150$, but I have no idea where to get a copper tube of that thickness.

Not sure where to get one at that thickness or diameter, but a specialized plumbing supply company can get you most standard size and diameter of copper piping. That one is huge, though. In theory, this should work with smaller, but powerful magnets, and thinner tubes, correct?

I don't think you can make a permanent magnet any stronger as it is. There is a certain limit. I think the size matters in this case.

I can only find thin pipes for plumbing online, but I would really like the think one.

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

#15

Post by evan_ »

IgorPartola wrote: post #13
deletes wrote: post #10

Where can you buy something like that. A magnet is around 150$, but I have no idea where to get a copper tube of that thickness.

You really don't need anything as fancy. A small magnet and a narrow aluminum tube will do just fine. It won't be quite as impressive, but drop a pebble from the same height not through the tube and watch the delay for the magnet dropping. A four foot length of tube about 1/2 to 3/4 inch in diameter would do nicely. Edit: try cast iron if you must have a big pipe. It's likely to be much cheaper. The thickness shouldn…

it's a less impressive demo if the pipe is made out of something ferrous, like cast iron.

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

#17

Post by klodolph »

IgorPartola wrote: post #13
deletes wrote: post #10

Where can you buy something like that. A magnet is around 150$, but I have no idea where to get a copper tube of that thickness.

You really don't need anything as fancy. A small magnet and a narrow aluminum tube will do just fine. It won't be quite as impressive, but drop a pebble from the same height not through the tube and watch the delay for the magnet dropping. A four foot length of tube about 1/2 to 3/4 inch in diameter would do nicely. Edit: try cast iron if you must have a big pipe. It's likely to be much cheaper. The thickness shouldn…

Iron is ferromagnetic, so the magnet will stick to the tube and not fall through.

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

#20

Post by taliesinb »

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…

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/wiki/Flux_pinning [2] http://www.youtube.com/watch?v=7_ZgiumS41Q

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