Magnetic Moment, Electron Spin, Energy

[roeb]

Homework Statement

The PE of a magnetic moment in an external magnetic field is given by U = -u dot B. Calculate the difference in energy between the two possible orientations of an electron in a magnetic field B = .6k T

Homework Equations

The Attempt at a Solution

I realize electrons can have an up spin and down spin, but I am having a hard time doing this problem.

I believe I should be using g = 2 for the gyromagnetic ratio. So: (_h = h bar)
u_z = -g u_B J_Z/_h
u_B = e(_h)/(2m_e)

Unfortunately then I don't know what I should have for J_z. (This is defined by my book as "any type of angular momentum).

So I guess my problem is that I don't know what I should use for angular momentum, since n and l aren't defined in the problem. Can anyone help clear this up?

 

[borgwal]

Use the electron spin, S_z. Strange you would know about the gyromagnetic ratio but not about which angular momentum that refers to in the case of an electron!