Friday, October 30, 2015

quantum mechanics - Spin and its connection to magnetic field


How the intrinsic spin of an electron results in a magnetic field? How does spin couples to the magnetic field? I mean to ask how does the phenomenon of Spin orbit coupling happens physically? Is the electron really spinning or not?



Answer



The electron is not spinning. Elementary particles are considered to be point-like particles, meaning that they do not have an internal structure. The spin is, as you say, an intrinsic property of particles. It is a pure quantum mechanical property that particles just have. The spin induces a spin magnetic moment: $$\vec{\mu_{s}}=g\frac{q}{2m}\vec{S}$$ So if an external magnetic field is applied, it will exert a torque on the particle's magnetic moment depending on its orientation with respect to the field. $$\vec{\tau}=\vec{\mu}\times\vec{B}$$


No comments:

Post a Comment

classical mechanics - Moment of a force about a given axis (Torque) - Scalar or vectorial?

I am studying Statics and saw that: The moment of a force about a given axis (or Torque) is defined by the equation: $M_X = (\vec r \times \...