Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What is permanent magnet B field equation?

  1. Feb 11, 2009 #1
    I'm looking for an equation to calculate Tesla (B) between two permanent magnets with distance of 10mm.

    Magnets are located in front of each other; disk shape and intensity of each is 1.3T in its core, and 0.6T on surface, so I'm interested how to calculate the B between them in distance of 5mm from each one (10mm between 2 magnets).

    Please help me to find proper calculation.
    Thanks in advanced.
  2. jcsd
  3. Feb 11, 2009 #2


    User Avatar
    Science Advisor

    If the magnets are much longer than 5mm, the B field 5mm from the face of one magnet is the same as the E field 5mm from a uniformly charged disk with charge density
    [tex]\sigma=M[/tex] where M=13,000 gauss (all in Gaussianl units). Just double it for two magnets.
  4. Feb 13, 2009 #3
    Thanks for your fast response.
    It seems OK, but in a short form I'm looking for a formula to calculate the Tesla in distance between two magnets.
    Suppose we have some parameters: dimensions of magnets, power of magnets in core and surface, distance between them; so how can we use a formula to calculate intensity between magnets in some distance?

    (Frankly I'm looking for a formula to use for my calculations)

    Attached Files:

  5. Feb 13, 2009 #4


    User Avatar
    Science Advisor

    The on axis formula for E due to a uniformly charged disk is in most (even elementary) textbooks.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook