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Strength of a permanent magnet

  1. May 30, 2008 #1
    Permanent magnets are advertised as having some scalar strength, say, 1.5 Teslas, depending on the composition of the magnet but not its volume. I'm confused about what this means. Shouldn't the magnitude of the magnetic field vary depending on where you measure it? And if I epoxy together two equally-oriented magnets, I would expect that the magnitude of the magnetic field, at a sufficient distance from the magnets, would be approximately twice the strength of that of one of the magnets alone.
  2. jcsd
  3. Jun 5, 2008 #2
    Flux density is measured at the surface of the magnet and varies with the distance from the surface. For more info, visit the magnet FAQs at

  4. Mar 14, 2009 #3
    Yeah if you coupled two identical Magnets together North to South you would approximately double the strength of the magnet.
  5. Mar 15, 2009 #4


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    Coupling two magnets together increases the strength at large distances where the magnet looks like a dipole, but not at short distances. Near a face, or at a distance
    d<L, there would be little change in the magnetic field. It could be slightly larger or slightly smaller depending on the location.
  6. Mar 17, 2009 #5
    The field strength at the face of the magnet does about double by stacking two magnets together. Just did a simple test with some disk magnets I have to confirm this.

    The reasons is that the flux will be channeled in the magnetic susceptible material and therefore will add together.
  7. Mar 18, 2009 #6


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    I thought you were talking about bar magnets. It is correct that disk magnets would add.
    But I think they should be placed N to N. Placing them N to S should cancel their fields.
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