1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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?

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook