Spin/Field Hamiltonian Consider a spin-1/2 particle with a magnetic moment u = -e/mS placed in a uniform magnetic field aligned along the z axis. (a) Write the Hamiltonian for this system in matrix...

Extracted text: Spin/Field Hamiltonian Consider a spin-1/2 particle with a magnetic moment u = -e/mS placed in a uniform magnetic field aligned along the z axis. (a) Write the Hamiltonian for this system in matrix form. (b) Verify by explicit matrix calculation that the Hamiltonian does not commute with the spin operators in the r and y directions. Comment on how this affects the expectation values of these operators.