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Physics project help -- magnetism

  1. Sep 19, 2014 #1
    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.
     
  2. jcsd
  3. Sep 19, 2014 #2

    Dale

    Staff: Mentor

    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.
     
  4. Sep 19, 2014 #3
    Can you expand on that? How would that work?
     
    Last edited by a moderator: Sep 19, 2014
  5. Sep 19, 2014 #4

    berkeman

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    Staff: Mentor

    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...
     
  6. Sep 19, 2014 #5

    Dale

    Staff: Mentor

    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.
     
  7. Sep 19, 2014 #6
    Photo on 9-19-14 at 5.00 PM.jpg Could this type go magnet be made?
     
  8. Sep 19, 2014 #7
    Above
     
  9. Sep 19, 2014 #8

    Dale

    Staff: Mentor

    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.
     
  10. Sep 19, 2014 #9

    Dale

    Staff: Mentor

    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.
     
  11. Sep 20, 2014 #10

    CWatters

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    Science Advisor
    Homework Helper

    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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