Module Identifier PH21510 Module Title THERMAL PHYSICS 1 Academic Year 2001/2002 Co-ordinator Dr Rudolf Winter Semester Semester 1 Other staff Dr Philip Cadman Pre-Requisite Core Physics Modules at Level 1 Course delivery Lecture 20 lectures. Seminars / Tutorials 2 seminars/workshops/exercise classes; 2 tutorials. Assessment Course work Example Sheets Example Sheets 1,2,3,6,7 & 8 Deadlines are detailed in the Year 2 example Sheet Schedule distributed by the Department 30% Exam 2 Hours End of Semester Examinations 70%

#### Module objectives / Learning outcomes

After taking this module students should be able to:

• understand the principles of the zeroth, first and second laws of thermodynamics and apply the three laws to solve associated problems
• explain diffusion, heat conduction and viscosity in terms of transport properties
• calculate quantities given by kinetic theory e.g. effusion rate, collision frequency etc.
• explain variations of heat capacity of gases with temperature in terms of population of energy levels
• identify the principal thermodynamic steps in the operation of heat engines and calculate efficiencies
• be familiar with the basic concepts of reversibility and entropy.

#### Module description

Thermal Physics deals with material properties and processes related to the conversion of heat and work and vice versa. Thermal processes can be understood at the atomic as well as the macroscopic level, and both approaches are introduced here. The laws of thermodynamics have been derived from empirical observations of gases, but they are applicable universally. The concepts of heat, work, reversibility, entropy and the steady state are central to many other areas of physics. Thermal Physics can explain the workings of heat engines, refrigerators and power stations by balancing the heat and work exchanged in each step of their operation cycle. On the atomic level, pressure can be understood as the summed impact of the collisions of gas molecules on the container walls. This is the idea of the kinetic theory, which leads to the thermal distribution of velocities and more generally to the population of energy levels. Many processes are irreversible, showing that an energy balance is not sufficient to predict the direction of a process. Entropy is introduced to take into account the dissipative nature of irreversible processes and to quantify the influence of disorder on the probability of a process.

#### Outline syllabus

LAWS OF THERMODYNAMICS

• ideal gas:

- Boyle-Mariotte et al.
- state variables, equations of state
- ideal gas law, R
- van der Waals
- critical point

• kinetic theory of gases:

- derivation of pressure from mechanical reasoning
- Maxwell-Boltzmann, rms-mean-probable speed
- temperature and population of energy levels

• zeroth law:

- thermal equilibrium
- temperature and temperature scales
- thermal expansion

• first law:

- heat, work, internal energy
- isothermal, isobaric, and adiabatic processes
- heat capacity, latent heat

• second law:

- all these funny engines and stuff
- Kelvin-Planck, Clausius statements
- reversible and irreversible processes, efficiency
- Carnot cycle and theorem
- thermodynamic temperature scale

• mathless introduction to entropy:

- direction of processes, order, disorder
- entropy and irreversible heat transfer
- thermodynamic probability

• transport properties:

- diffusion, heat conduction (mechanical)
- diffusion, heat conduction (microscopic)