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Difference in Magnetic Poles

  1. Oct 10, 2012 #1

    Physicist50

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    I was wondering what the difference in the magnetic poles north and south is and what makes them unique.
     
  2. jcsd
  3. Oct 10, 2012 #2

    phinds

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    One is North and the other is South.
     
  4. Oct 11, 2012 #3

    Physicist50

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    Indeed, but what makes one magnet north and one magnet south? Is there a difference in atomic or molecular structure, or the way they work?
     
  5. Oct 11, 2012 #4
    They are fictitious entities that correspond to what is commonly known as the Gilbert model of a magnetic dipole. It treats magnetic material as consisting of tiny dipoles comprised of fictitious point magnetic charges (monopoles), in analogy with real electric dipoles that can exist in a dielectric material. When such dipoles are uniformly aligned along say a bar magnet, one face is then considered to be exposed to north magnetic charges, the other to south magnetic charges. This picture is consistent with the correct external magnetic field generated by such a permanent magnet - although in real magnets magnetization is never completely uniform and the 'magnetic charge' distribution is somewhat more complicated than just charges at each end face.

    A rival Ampere model is considered more fundamental as it provides a picture closer to what is actually thought to apply to real intrinsic magnetic dipoles. It treats the fundamental dipoles as composed of tiny current loops, and when these are aligned in a bar magnet, internal currents essentially cancel, leaving surface currents on the side surfaces that correspond to a solenoidal distribution. There is then no north and south poles. The Ampere model gives the same external field as Gilbert model, but yields a very different result for the internal field. Normally this doesn't matter as only the external region is accessible. Wikipedia has some good info: http://en.wikipedia.org/wiki/Magnetic_dipole
    http://en.wikipedia.org/wiki/Magnetic_moment
     
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