Why does the electron have a magnetic moment?

[carllacan]

Hi.

I thought magnetic moment arose from closed loops of charge currents. How does then the angular momentum of the electron produce a magnetic moment? I mean, the electron is not a loop.

Am I wrong in my initial assumption or am I understanding things too "classically"?

Thanks.

 

[Meir Achuz]

You are thinking too classically. The electron's magnetic moment arises from the relativistic QM Dirac equation for the electron.

 

[dextercioby]

You don't need Dirac's equation to derive the magnetic moment of the electron. Pauli's nonrelativistic equation will suffice.

 

[carllacan]

I see. Then saying that the magnetic moment arises from its rotation and its charge is just oversimplifying things, right?

 

[Meir Achuz]

Right. Pauli's equation can include the moment, but does not derive it as a necessity.

 

[dextercioby]

Pauli's equation always includes the magnetic moment, because it automatically includes the spin.