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Full Year

Thermal Physics (PHYS09061)

Subject

Physics and Astronomy

College

SCE

Credits

20

Normal Year Taken

3

Delivery Session Year

2023/2024

Pre-requisites

None

Course Summary

This two-semester course covers thermal physics, the first semester contains an introduction to equilibrium thermodynamics. The First and Second laws of thermodynamics are introduced, along with the concepts of temperature, internal energy, heat, entropy and the thermodynamic potentials. Applications of thermodynamic concepts to topics such as heat engines, the expansion of gases and changes of phase are considered. The Third Law, and associated properties of entropy, complete this section.The second semester provides an introduction to the microscopic formulation of thermal physics, generally known as statistical mechanics. We explore the general principles, from which emerge an understanding of the microscopic significance of entropy and temperature. We develop the machinery needed to form a practical tool linking microscopic models of many-particle systems with measurable quantities. We consider a range of applications to simple models of crystalline solids, classical gases, quantum gases and blackbody radiation.

Course Description

Thermodynamics (semester 1):- Thermal equilibrium; equations of state and thermodynamic stability; PV diagrams; temperature scales. - First law: heat and work; reversible and irreversible processes; heat capacities. - Thermodynamic processes: reversible expansions (isothermal, adiabatic); irreversible expansions (Joule, Joule-Kelvin); illustration with ideal and van der Waals gases. - Second law: entropy from a thermodynamic perspective (Clausius, Kelvin-Planck definitions). - Cyclic processes: Carnot cycle, maximum efficiency. - Thermodynamic potentials; Legendre transformations; Maxwell relations; applications to various thermodynamic processes. - Introduction to Black Body radiation (treated more fully in Statistical Mechanics). - Thermodynamic approach to phase transitions; van der Waals as example; continuous and discontinous transitions; critical point. - Third law. - Chemical potential and open systems.- Superconductivity and superfluidity as concepts. Statistical Mechanics (semester 2):- Statistical description of many-body systems; formulation as a probability distribution over microstates; central limit theorem and macrostates. - Statistical mechanical formulation of entropy. - Minimisation of the free energy to find equilibrium. - Derivation of the Boltzmann distribution from principle of equal a priori probabilities in extended system.- Determination of free energy and macroscopic quantities from partition function; applications to simple systems (paramagnet, ideal gas, etc). - Multi-particle systems: distinguishable and indistinguishable particles in a classical treatment; Entropy of mixing and the Gibbs paradox. - Fermi-Dirac distribution; application to thermal properties of electrons in metals.- Bose-Einstein distribution; application to the properties of black body radiation; Bose-Einstein condensation.

Assessment Information

Written Exam 80%, Coursework 20%, Practical Exam 0%

Additional Assessment Information

Coursework 20%Examination 80%

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