I understand that the magnetic moment of an electron is associated with its intrinsic spin. But what is the magnetic field due to spin? I'm asking this while thinking about the Faraday Effect where the magnetic field in the direction of the light's propagation is due to the spin of an electron. The angle of rotation is constant * distance * magnetic field. What do I put in for magnetic field? The only thing I see is the magnetic moment but that does not have the right units. Thanks.