TITLE: How is the spin angular momentum $h/4\pi$ determined?
QUESTION [0 upvotes]: We can determine the orbital angular momentum by $mvr$, how is the intrinsic spin angular momentum of an electron?

REPLY [0 votes]: The orbital angular momentum is determined by $L=\sqrt{1\left( l+1\right) }\cdot \dfrac{h}{2\pi }$, where $l$ is the azimuthal quantum number and the spin angular momentum is determined by $S=\sqrt{s\left( s+1\right) }\cdot \dfrac{h}{2\pi }$, where $s$ is the spin quantum number.
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