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Homework Help: Magnetic field of a bar magnet

  1. Nov 25, 2009 #1
    1. The problem statement, all variables and given/known data

    I have a problem in my upper div. lab which uses a series of magnets to make a magnetic field. I need to explain the field in some way to show what we did mathmatically. The set up can basically be considered as a magnetic dipole with two mono poles due to insulators.

    N||||| S

    Help me solve for B in some way

    2. Relevant equations

    B = uM + H ?

    3. The attempt at a solution

    Tried to do it by approximation of a loop dipole analogy but it was seperating the length of the poles not the width between them. Any help even just to get started will be appriecated i've tried for soooo long to get any results
  2. jcsd
  3. Nov 25, 2009 #2


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    Homework Helper

    I'm not entirely clear on what you're asking, but perhaps you could consider making an analogy to an electric dipole - basically just treat it as two monopoles separated by a certain distance.
  4. Nov 25, 2009 #3
    sorry, i'm trying to figure out the generalized equations for the magnetic field above a physical dipole. I was trying to clarify that i was ignoring the fact that the poles were continuous and wanted to treat them as point poles in a sense. i'll try the electrical analogy and see if it works thank you.
  5. Nov 25, 2009 #4
    ok so i got B = (u0/4π)(1/r^3)[3(m*rhat)rhat - m] but i still can't use m for this because m is IA and i don't want loop area i want area between the tops of two different loops. Halp
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