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What makes a permanent magnet a permanent magnet?

  1. Nov 14, 2007 #1
    I have searched and searched but do not know what gives rise to a permanent magnet. I would like to know why two opposite forces are produced at the ends of the magnet. The closest I have got to it is to do with electron spins becoming aligned.

    Help would be most appreciated

    Thank you
     
  2. jcsd
  3. Nov 14, 2007 #2
    First make sure you understand "what gives rise to an electromagnet". (If you look deeply, by the way, you'll find an answer is special relativity combined with the familiar Coulomb repulsion between electrons.)

    Permanent magnets are just the same, except rather than having a classical current of free electrons around a (preferably super-conductive) wire, you need quantum mechanics which basically says that many of the individual bound electron "probability waves" are rotating around their respective atomic nuclei.
     
    Last edited: Nov 14, 2007
  4. Nov 16, 2007 #3
    Permanent magnets have groupings of "bodies" of alloyed materials that under pressure and elevated temperature are subjected to an intense short-duration magnetic field. Those bodies align based upon their internal magnetic potential. That potential is determined by the alignment of micro crystaline forms of electro-energetic elements such as Iron. Such elements have dipoles associated with their microcrystaline form. That dipole is created by the "cell" structure of the crytal being electro deficient in one plane. This plane is the longitudinal axis of that crystal's magnetic dipole. Now think of a sliver of Iron like the needle of a compass. When the temperature and pressure are increased in its surroundings the sliver is freed up to rotate and associate with any magnetic dipole that can influence it. The surroundings that it is in is other slivers that are trying to line up as well. when a magnetic field of sufficient strength is applied to this matrix in this condition then all of the slivers line up together (this is instantaneous and so the applied magnetic field need last only a thousandth of a second). At this point the magnet is cooled. Yes, if you wait too long to cool the magnet it will loose quite a bit of magnetism, but the rate of loss is minimised by several factors. One is that the matrix can be a ceramic mixture rather than an alloy allowing for lower temperatures in manufacture, but this also has the tendency to be demagnetised by stronger fields. Permanent magnets are permanent only as long as they are not subjected to a magnetic field of sufficient strength to negate or erase the field in the magnet, also based upon material resistance to loss of magnetism (see the ceramic above). They are also subject to extreme temperatures (as seen in the manufacturing process). I hope this answers you r questions to some degree, see ya, BAT
     
  5. Oct 10, 2010 #4
    Re: Magnetism

    can u be more elaborate in explaining ... how is relativity causing the rise of electromagnet...
     
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