1. Lecture 12-- CALM The so-called two-level system is a model that finds many uses in physics. In this model, the system is assumed to have only two states in which it can exist, and these states are separated in energy by an amount Δ. Consider a situation in which such as system in which Δ is 0.02 eV is in thermal contact with a temperature reservoir at temperature T. At what value of T will the system be half as likely to be in the upper level as it is to be in the lower level? ~335 K from ln(0.5)=-  /kT (5 answers). Other (5 answers). No answer: 8

2. Chapter 5 Example

3. Let’s consider the particle in a box problem yet again. The energy levels are given by (we’ll take the box to be a cube of side L):  (nx,ny,nz) = (h 2 /8mL 2 )[ n x 2 + n y 2 + n z 2 ] (4.5) What is the ratio of the probabilities for the particle to have each of the three lowest energies in this model? What is the temperature at which each of these ratios would start to vary appreciably for the case of an electron confined in a cube with L=10nm?

4. Correction to HWA#5 Q3