Question

Two values of spin quantum numbers ie., $+\frac{1}{2}$ and $-\frac{1}{2}$ represent:

• A. up and down spin of the electrons respectively
• B. two quantum mechanic spin states which refer to the orientation of spin of the electron
• C. clockwise and anti-clockwise spin of the electrons respectively
• D. anti-clockwise and clockwise spin of the electrons respectively

Answer 1

The correct option is C clockwise and anti-clockwise spin of the electrons respectively

An electron with spin = 1/2 can have two orientations +1/2 or -1/2 in the presence of magnetic field. The orientations are represented by the magnetic spin quantum number ms. Here + and - sign are in relation to the direction of the magnetic field. It is arbitrary that in most of the text books the magnetic field direction is usually chosen along z-direction. Thus, +1/2 represents the component of spin vector pointing along positive z-direction and -1/2 represents that the component of spin vector pointing along negative z-direction.
Hence, option(C) is the most correct option.