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: 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