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!

Deriving the Magnetic Field from a Magnetic Dipole

  1. Apr 15, 2015 #1
    1. The problem statement, all variables and given/known data
    Show that: ##B=\frac { 1 }{ 4\pi \epsilon r^{ 3 } } \left[ 3\hat { r } \left( \hat { r } \cdot \vec { m } \right) -\vec { m } \right] ##

    2. Relevant equations

    B=delxA, m=a*I

    3. The attempt at a solution

    I follow my professors derivation. However, she expands the term: ##\vec { \nabla } \times \left( \vec { m } \times \vec { r } \right) =2 \vec m## by just using the determinate. I figured I would go with the less messy "BAC CAB" like she uses on another term. However, I can't get ##2 \vec m## by using BAC CAB. I get ##3 \vec m## instead. I have tried both ways using spherical and cartesian. Does not ##\nabla \cdot \vec m=0##? If I can show that ##\vec { r } \left(\vec \nabla \cdot \vec m \right)=-\vec m##. I would be home free, but I think it should equal zero.

    Any E&M or vector calc. gurus, your help would be appreciated.

    Thanks,
    Chris Maness
     
  2. jcsd
  3. Apr 15, 2015 #2

    TSny

    User Avatar
    Homework Helper
    Gold Member

  4. Apr 15, 2015 #3
    Dang, ok. That was a pretty basic oversight. Thanks

    Chris
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Deriving the Magnetic Field from a Magnetic Dipole
Loading...