Nnon-interactive classical particles with a magnetic momentu are in a uniform magnetic field, b. the particles are fixed on each site of a lattice. the only freedom of a particle is its magnetic moment to be parallel or anti-parallel to the magnetic field (ui=-u oru, i=1,). the system is in equilibrium with the environment at temperature t. a) obtain the helmholtz free energy; b) obtain the averaged total magnetic moment along the magnetic field, m =< si=1 mi > , of the system.