Physics project help -- magnetism

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Is it possible to make a magnet that slides down a pole with no friction? The magnet would be a cylinder, the exterior would be N and the interior S. It would slide down the S end of a magnetized pole. That way the the pole would push equally on the sides of the interior of the cylinder. This is for my middle school science fair.
 

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  • #2
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You cannot have a magnet whose exterior is a north pole. That would be a magnetic monopole and would be a Nobel prize project, not a middle school science fair project.

You could have bar magnets that slide through a copper tube, or something similar.
 
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You cannot have a magnet whose exterior is a north pole. That would be a magnetic monopole and would be a Nobel prize project, not a middle school science fair project.

You could have bar magnets that slide through a copper tube, or something similar.
Can you expand on that? How would that work?
 
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  • #4
berkeman
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Is it possible to make a magnet that slides down a pole with no friction? The magnet would be a cylinder, the exterior would be N and the interior S. It would slide down the S end of a magnetized pole. That way the the pole would push equally on the sides of the interior of the cylinder. This is for my middle school science fair.
You cannot have a magnet whose exterior is a north pole. That would be a magnetic monopole and would be a Nobel prize project, not a middle school science fair project.

You could have bar magnets that slide through a copper tube, or something similar.
It seems like you could bolt together a number of thin rectangular magnets in the shape of a cylinder, with their S ends pressed together at the inner radius, and the outer N ends spaced a bit apart.

But even with that, you couldn't have a "pole" that was the S end of a magnet, so the overall idea still doesn't seem to work.

You could look into how maglev trains work -- that will give you an idea of a geometry that uses magnetic levitation to minimize friction...
 
  • #5
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Just buy some cylindrical bar magnets and then buy a copper tube that is slightly wider. You can use that kind of rig to demonstrate eddy currents.
 
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Photo on 9-19-14 at 5.00 PM.jpg
Could this type go magnet be made?
 
  • #7
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Just buy some cylindrical bar magnets and then buy a copper tube that is slightly wider. You can use that kind of rig to demonstrate eddy currents.
Above
 
  • #8
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Ah, I completely misunderstood the geometry. I would call that shape a tube, not a cylinder. Please disregard my previous comments. I believe that you could indeed have a tube magnet with the poles as described in your OP. My apologies.
 
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  • #9
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You want to look for a radially magnetized ring or tube magnet. They are apparently difficult to manufacture, so they are going to be expensive.
 
  • #10
CWatters
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You can make a ring magnet with S on the inside and N on the outside.

However making the long magnetised pole for it to slide down is more of a problem. The further you get from the ends of the more it looks like a monopole from the outside.
 

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