Reif, problem 11.2. The magnetic susceptibility x = a MaH (where and H are the mean magnetization and magnetic field). Hint: show that the relation: Tds = dE + MdH can be written as dF (T,H) = d(E TS) = -SDT MdH , from which derive the so-called Maxwell relation h (see box on p.450) as , H OH