1. The Laws of Thermodynamics
Zeroth law
First law: Energy conservation
Third law
Second law

2. Other Results from Thermodynamics
Equipartition
Degrees of Freedom
Stefan-Boltzmann Law
Wien’s Displacement Law
Phase Diagrams
l Tmax = const.

3. Quasi-static processes
Quasi-static processes: near equilibrium
States, initial state, final state, intermediate state: p, V & T
well defined
Sufficiently slow processes = any intermediate state can be considered as at thermal equilibrium.
Criterion: It makes sense to define a temperature (ie)
there is a statistical average
Examples of quasi-static processes:
- iso-thermal: T = constant
- iso-volumetric: V = constant
- iso-baric: P = constant
- adiabatic: Q = 0

4. State functions a b c a. isovolumetric b. isobaric a. isobaric
b. isovolumetric
isothermal
the work done by a system depends on the initial and final states and
on the path  it is not a state function.
energy transfer by heat also depends on the initial, final, and intermediate states
 it is not a state function either.

5. Summary Thermodynamics is just an equilibrium theory.
But natural processes are usually not in eq. and irreversible.
 Kinetic theory; statistical mechanics
Summary
Quasi-static
process
Character
isovolumetric
V = constant
isobaric
P = constant
isothermal
T = constant
adiabatic

6. Blackbody Radiation
Spectral energy density
of a black body

8. Test Plot: Planck formula vs. Wien, Rayleigh

9. Source Wikipedia

10. BBD Theory EM field in a box as superposition of standing waves
Planck: quantize as n* hf
Planck Distribution
Modes with hf>>kT are
exponentially suppressed

11. Summing over modes in 3d
for photons
The spectrum of the photons

12. Best confirmation: Cosmic Background Radiation
Summing over all frequencies gives the total energy
(the Gaussian integral yields pi^4/15)
Best confirmation: Cosmic Background Radiation

13. Fitting solar radiation by BBD

14. X-Ray diffraction

15. Bragg’s law:

16. 14 Spatial Lattices

17. Visualizing Cubic Lattices

18. Symmetry in Cubic Lattices

19. Hexagonal lattices

20. Miller Indices ~ describing planes
in 3d Lattices

23. Reciprocal Lattice

24. Brillouin Zones and Wigner Seitz cells

25. Reciprocal lattice
Diffraction pattern

26. Spectral lines and Symmetry

27. X-Ray Spectra ~ Interpretation

28. Powder Spectra

29. X-rays, practical issues
Rev Sci Instr 3/1939

30. Microwave Radiation, Microwave Horns
J Singal et al.
Typical microwave triode design

31. Horn Gain fct of angle
Reflection loss horn

32. Theory of EM Horns
1939, reprinted 2006

33. Pyramidal horns, optimal dimensions
Horn antenna types, wikipedia
John Kraus ‘Antennas’