Question

[3] From MSU Graduate Qualifying Exam, Jan. 7, 1999: Consider a gas of noninteracting atoms in a magnetic field Bêz in the z-direction. Each atom has total spin ½ Each atom has a permanent dipole moment, with magnitude mo, in the direction of the spin; for spin up m-moêz, and for spin down m-moêz. The magnetic energy of the atom is -moB for spin up, and +moB for spin down. a) Determine the mean dipole moment of an atom as a function of the temperature T. Recall that the probability for a system to be in a state with energy E is proportional to -EIKT b) Sketch a graph of the mean dipole moment versus T.

Answer 1

b Shiun B. p e FE K T ;-. k T-In-- taab.h @lusk.) -

KT KT KH) A。