Thermal Physics I

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  • Lecture 0. [Invitation to Thermal Physics]
  • Lecture 1. [Thermometry & Calorimetry]
  • Lecture 2. [Introduction to K.T.]
  • Lecture 3. [Solid Angle Concepts]
  • Lecture 4. [Pressure using Solid Angle]
  • Lecture 5. [Gas Laws]
  • Lecture 6. [Maxwell Distribution]
  • Lecture 7. [Cm, Cavg, Crms]
  • Lecture 8. [Energy & Momentum Distribution]
  • Lecture 9. [Degrees of Freedom]
  • Lecture 10. [Mean Free Path]
  • Lecture 11. [Gas laws using Mean Free Path]
  • Lecture 12. [Viscosity & Thermal Conduction]
  • Lecture 13. [Diffusion & Law of Atmosphere]
  • Lecture 14. [Einstein-Langevin Theory]
  • Lecture 15. [van der Walls equation]
  • Lecture 16. [Virial Theorem]
  • Lecture 17. [Heat Conduction]
  • Lecture 18. [Peridic & Curvilinear Heat Flow]
  • Lecture 19. [Kirchoff's law of Radiation]
  • Lecture 20. [Wien's, Stefan's, Newton's and Planck's law]
  • Lecture 21. [UV Catastrophe and Temperature of Sun]


Study Materials

  1. Thermal Physics - A.B. Gupta & H.P. Roy.
  2. A Treatise on Heat - Meghnad Saha & B.N. Srivastava.
  3. Elements of Nonequilibrium Statistical Mechanics - V.Balakrishnan.
  4. Feynman Lectures on Physics (Vol 1) - R.P. Feynman .
  5. Statistical Physics Part-1 (Vol 5) - L.D. Landau and E.M. Lifshitz.
  6. Fundamentals of Statistical and Thermal Physics - F. Reif .


  1. Kinetic Theory of Gases: Basic assumptions of kinetic theory, Ideal gas approximations, deduction of perfect gas laws, Maxwell's distribution law in velocity and energy, root mean square and most probable speeds, Finite size of molecules: Collision probability, Distribution of free paths and mean free path from Maxwell's distribution, Degrees of freedom, equipartition of energy.
  2. Transport Phenomena: Viscosity, thermal conduction and diffusion in gases, Brownian motion, Einstein's theory, Perrin's work, determination of Avogadro number.
  3. Real Gases: Nature of intermolecular interaction: isotherms of real gases, van der Waals' equation of state, Other equations of state, critical constants of a gas, law of corresponding states, Virial coefficients, Boyle temperature.
  4. Conduction of Heat: Thermal conductivity, diffusivity, Fourier's equation for heat conduction - its solution for rectilinear and radial (spherical and cylindrical) flow of heat.
  5. Radiation: Spectral emissive and absorptive powers, Kirchoff's law, Blackbody radiation, energy density, radiation pressure, Stefan-Boltzmann law, Newton's law of cooling, Planck's law.


  1. Newton's law of cooling example: Adding creme to coffee.
  2. Numerical computation of (a) Heat Convection (Hot plate in air), (b) Heat Conduction in foam, (c) Heat Radiation in Flare ignition.
  3. Experiments on Critical Opalescence (1910). Read also about Einstein's work on critical opalescence.
  4. Pedagogic article on Einstein's legacy, by (a) SDG, (b) DC.
  5. Einstein's paper: Brownian Movement , Kubo's paper: Fluctuation Dissipation Theorem, Chandrasekhar's paper: Stochastic Process.
  6. Experiments with Newtonian (water) and Non-Newtonian (Oobleck) fluids - fun with science.
  7. If you do want to differentiate between different integration constant for u, v, w as (say) A,B,C, then also its equally valid. Notice then, dNu,v,w = NABC e-bc2 du dv dw, and then in integration over this gives, ABC =(b/pi)3/2 (instead of A3 = (b/pi)3/2). After substituting b, you'll get Maxwell's distribution back.
  8. Don't get confused with (i) number density(n) & number (N) as they appear in both sides of the equation and can be easily transformed back and forth. Similarly, density and number density differs only by "m" and for unit mass both is equivalent.