PHYS 317 - Reading Assignment #18

  1. Why is the average energy per atom related to the total thermal energy U?

    A single atom can be thought of as the ``system'' and all the remaining atoms thought of as the ``reservoir.'' We compute the average energy for this single atom at this temperature. Then, since there was nothing special about the atom we chose, we can conclude that all N atoms will have the same average energy, so U = N*Eavg.

  2. What is the partition function for a single dipole (a "spin") in the two-state paramagnet?

    Z = ebeta*mu*B + e-beta*mu*B = 2 cosh(beta*mu*B).

  3. Where does the factor (2j+1) in equation (6.30) come from?

    For an angular mometum vector with magnitude j there are 2j+1 different possible orientations, all different states but having the same energy.
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