[UPSC CSE 2001] Angular momentum, spin etc (Q334, (10+20)M)

(i) Give briefly an account on the important historical developments to establish the concept of electron spin. (ii) Write down the eigenvalue and spin state of an electron for the spin operator \hat{S}. (i) Show that the spin states of electron are orthogonal to each other. (ii) State the spin angular momentum commutation relations. (iii) Give the explicit forms of all the Pauli spin matrices.