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Homework Help: About magnetized spheres

  1. Oct 11, 2008 #1
    Hi ...

    how can I calculate the force between two permanent magnetized spheres(each r in radius) and has a magnetization (M) when they are magnetically stuck together with unlike poles touching??

    I tried to think about it and found the following:

    1) I can treat it like earth magnetic field and imagine there is a bar inside the sphere.
    2) because there is no distance between the spheres I must calculate the force for one sphere then multiply it by 2.
    3) the formula must have the M,V, meu( permeability of free space). but I can't find such formula which give me the right result ( yes I have the answer in number, it is GRE question)

    thanks in advance.
    Last edited by a moderator: Oct 13, 2008
  2. jcsd
  3. Oct 12, 2008 #2
    you mean uniform magnetization throughout?

    the distance between them is 2r
  4. Oct 12, 2008 #3

    the question is exactly like that

    ( A permanent magnet alloy of samarium and cobalt has a magnetization M= 7.5*10^5 J/T.m^3 . Consider two magnetized spheres of this alloy each 1 cm in radius and magnetically stuck together with unlike poles touching. What force must be applied to separate them??)

    Note: before I post my question I tried the distance 2r but still i can't find the right result !! what is the formula??

  5. Oct 13, 2008 #4
    isn't here suitable for this kind of questions ? or I must put it in another branch?

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