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Magnetic quadrupole

  1. May 26, 2015 #1
    I have heard of a magnetic quadrupole. It is often represented as 4 bar magnets separated and arranged in such a way that for any 1 magnet it is attracted to the magnets 90 degrees from it but is repelled by the magnet 180 degrees from it. I have tried to form it with earth magnets thinking that the stronger the magnet the more likely it is to form a quadrupole. But I have had no success. I successfully get the 4 magnets separated and at angles of 180 and 90 degrees making sure that the ones at 180 degrees repel and the ones at 90 degrees attract.

    However the problem comes when I get rid of what is separating the magnets. Either 1 of the magnets turns 180 degrees or it flips or it turns 90 degrees. Either way pairs of magnets attach themselves.

    How can I have magnets in open space form a quadrupole?
  2. jcsd
  3. May 26, 2015 #2
    Why do you assume the quadrupole arrangement is stable on its own? I'm pretty sure it isn't.
  4. May 26, 2015 #3
    I assume that because I have always seen it represented as 4 magnets in open space.
  5. May 26, 2015 #4
    I think the arrangement is a classic example of an unstable equilibrium. In perfect positions there are no net forces, but even the slightest deviation will make it collapse.
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