Answer Happy

Problem 1.7. Thermometers (a) Describe some of the simple thermometers with which you are familiar. (b) On what physical principles do these thermometers operate? (c) What requirements must a thermometer have to be useful? To gain more insight into the meaning of temperature we consider a model thermometer known as a "demon." This demon is a special particle that carries a sack of energy and exchanges energy with the system of interest. If the change lowers the energy of the system, the demon puts the extra energy in its sack. If the change costs energy, the demon gives the system the needed energy with the constraint that Ed, the energy of the demon, must be nonnegative. The behavior of the demon is given by the following algorithm: 1. Choose a particle in the system at random and make a trial change in one of its coordinates. 2. Compute AE, the change in the energy of the system due to the trial change. -→ 3. If AE < 0, the system gives the surplus energy |AE| to the demon, Ed — Ed +|AE|, and the trial change is accepted. 4. If AE > 0 and the demon has sufficient energy for this change (remember that Ed is non- negative), then the demon gives the necessary energy to the system, Ed → Ed - AE, and the trial change is accepted. Otherwise, the trial change is rejected and the microstate is not changed 5. Repeat steps 1-4 many times. 6. Compute the averages of the quantities of interest once the system and the demon have reached equilibrium. Note that the total energy of the system and the demon is fixed. We consider the consequences of these simple rules in Problem 1.8. The nature of the demon is discussed further in Section 4.9.