Department of Physics, Unit Catalogue 2006/07 
PH40069 Thermal physics 
Credits: 6 
Level: Masters 
Semester: 1 
Assessment: EX80CW20 
Requisites: 
Before taking this unit you must (take PH10002 or take PH10052) and take PH10007 and take PH10008 
Aims: The aims of this unit are to develop an indepth understanding in both physical and mathematical terms of the concepts of classical thermodynamics and their application to physical processes and to introduce the concepts of statistical mechanics, showing how one builds from an elementary treatment based on a description of microstates to a mathematical description and solution of a variety of models for manybody systems.
Learning Outcomes: After taking this unit the student should be able to: * define and understand and discuss the relevance of thermodynamic terms such as temperature, equilibrium, function of state, reversibility; * understand and apply the 1st and 2nd laws; * define entropy and the common thermodynamic potentials and understand their importance to phase changes; * appreciate the need for a microscopic approach to thermal physics and demonstrate an understanding of the microstate formalism and be proficient in its application; * derive the appropriate thermodynamic potentials from the partition function of simple models and use appropriate approximations to tackle less simple models; * calculate averages of observables, heat capacities and other thermodynamic variables for simple models; * describe the FermiDirac, BoseEinstein, Boltzmann and Planck distribution functions and apply them to simple models; * show proficiency in the mathematical formulation and solution of a variety of problems in thermal physics. Skills: Numeracy T/F A, Problem Solving T/F A. Content: Overview (1 hour): Macroscopic and microscopic approaches to thermal physics. Classical thermodynamics (8 hours): Basic thermodynamic concepts. The second law of thermodynamics. Entropy. Analytical thermodynamics; application to phase changes. Statistical mechanics (8 hours): Microstates and macrostates of an isolated system, density of states, partition function. Principle of equal a priori probabilities; entropy, equilibrium and the second law. Systems in thermal contact with heat reservoir; the Boltzmann distribution. Canonical ensemble. Free energy minimisation. Systems of weakly interacting constituents (2 hours): Ideal gas and indistinguishability. Equipartition theorem. Maxwellian gas. Quantum gases (2 hours): Indistinguishability. Fermions and bosons. Low density limit. Systems with variable particle number (1 hour): Grand canonical distribution; chemical potential. 
