1. Not finding help here? Sign up for a free 30min 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!

Magnetic moment

  1. Nov 13, 2008 #1
    Say I know the total angular momentum of my electron as J. If I write the total magnetic moment as [tex] \mu = \gamma J [/tex] then does [tex] \gamma = \gamma_{spin} + \gamma_{orbital} [/tex] ?
     
  2. jcsd
  3. Nov 14, 2008 #2

    malawi_glenn

    User Avatar
    Science Advisor
    Homework Helper

    yes, you have one contribution from orbital motion around nucleus and one from its intrinisc spin. The g-factors and so on of course differs so one has to be careful.
     
  4. Nov 14, 2008 #3

    clem

    User Avatar
    Science Advisor

    No. Mu will not be in the direction of J, since the g factor for S and L are different.
    For a single electron, [tex]{\vec\mu}=(-e/2mc)[{\vec L}+2{\vec S}][/tex].
    This is the origin of the Lande g factor.
     
  5. Nov 14, 2008 #4
    My research suggests one can define a [tex]\mu[/tex] in the direction of J with a Lande factor

    [tex] g_J= g_L\frac{J(J+1)-S(S+1)+L(L+1)}{2J(J+1)}+g_S\frac{J(J+1)+S(S+1)-L(L+1)}{2J(J+1)} [/tex]

    if one is measuring the total angular momentum, say in a magnetic resonance experiment. But as clem said, [tex] \mu_J \neq \mu_S + \mu_L [/tex].
     
  6. Nov 14, 2008 #5

    malawi_glenn

    User Avatar
    Science Advisor
    Homework Helper

    Ok, maybe my answer was not careful enogh, what I meant with "yes" was not referring to your result [tex] \gamma = \gamma_{spin} + \gamma_{orbital} [/tex]

    I didn't know at what level you was asking. Sorry
     
  7. Nov 14, 2008 #6

    clem

    User Avatar
    Science Advisor

    Mu will not be in the direction of J for a single electron. The Lande g factor is for the
    component of mu in the direction of J. It follows by dotting my formula for mu with J and doing some algebra, leading to Andrew's (and Lande's) formula.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Magnetic moment
  1. Magnetic moment (Replies: 3)

  2. Orbital magnetic moments (Replies: 15)

Loading...