** AKNU Third Semester Physics important Questions **

**Unit-1**

- What is the maxwell’s law of distribution of molecular speeds in a gas? Describe the experiment to prove it.

(Tooth wheel experiment). - Define coefficient of viscosity on the basis of kinetic theory gases. Derive an expression for the coefficient of

viscosity. - Define coefficient of thermal conductivity on the basis of kinetic theory gases. Derive an expression for the

coefficient of thermal conductivity. - Define coefficient of diffusion on the basis of kinetic theory gases. Derive an expression for the coefficient of

diffusion.

**Unit-2** - Describe the caront’s engine and its working. Derive an expression for its efficiency.
- State and prove Carnot’s theorem.
- What is T-S Diagram. Derive an expression of efficiency of a Caront’s engine using T-S diagram.

Write the uses of T-S diagram. - Describe the change in entropy in reversible and irreversible process.

**Unit-3** - Define four thermodynamic potentials and use them to derive maxwell’s thermodynamic equations.
- Explain the Joule -Kelvin effect. Derive expression for Joule – Kelvin effect for an Ideal gas. .
- Define molar specific heats.

Derive an expression for the difference of two specific heats (𝐶_{p}− 𝐶_{v}= 𝑅)

Derive an expression for the ratio of two specific heats (𝐶_{p}/𝐶v = y)

**Unit-4** - Explain the Joule Kelvin or Joule Thomoson effect. Describe porus plug experiment and write its results (OR)

Derive an expression for Joule-Thomson cooling. - Explain necessary theory the adiabatic demagnetization method for producing very low temperature.

**Unit-5** - Derive Plank’s formula for distribution of energy and deduce Raleigh – Jeans law as a special case of Plank’s law.
- Define solar constant. Explain how it is determined experimentally (OR) Explain Angstrom’s pyroheliometer.

**5 Marks****Unit-1** - Explain and derive the free mean path equation of a gas.
- Explain various types of Transport phenomena
- Derive the equation for Relation between coefficient of viscosity & coefficient of thermal conductivity.
- Derive the equation for Relation between coefficient of viscosity & coefficient of diffusion
**Unit-2** - Derive work done by an ideal gas in isothermal and adiabatic process.
- Explain reversible and irreversible process.
- State and explain the second law of thermodynamics (Kelvin & clausius).
- Derive an expression for the change in entropy when a substance undergoes change of state (ice changes to into

steam). - Explain about entropy and its physical interpretation.
- Distinguish between isothermal and adiabatic process.
- Problems
**Unit-3** - Derive Classius – Clayperon equation and write its applications.
- Explain the Joule -Kelvin effect.
- Problem
**Unit-4** - Give the applications or properties of low temperature. (M-6Q-71P)
- Distinguish between adiabatic expansion and Joule –Thomson expansion. (M-4Q-71P)
- Problems (72 page- 1,3 Questions)
**Unit-5** - Explain energy distribution in a black body radiation and its characteristics.
- How do you estimate the temperature of the sun? .
- Explain about black body and ferry’s black body.
- Define Kirchoff’s law, Stefan’s law, Wien’s displacement law and Rayleigh Jeans law.
- Problems