LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034

   B.Sc. DEGREE EXAMINATION – PHYSICS

THIRD SEMESTER – NOVEMBER 2010

PH 3505/PH 3503 – THERMODYNAMICS

 

 

 

Date : 02-11-10                     Dept. No.                                        Max. : 100 Marks

Time : 9:00 – 12:00

SECTION – A

Answer ALL the questions                                                                                         (10×2=20)

 

1. Define the mean free path and the mean free time.
2. Calculate the r.m.s. velocity for oxygen molecules at . Given mass of

oxygen is 5.31x and the Boltzmann’s constant k= 1.38x J/K.

3. Write down the equation of state for an ideal gas when it undergoes a (i) reversible isothermal and (ii) adiabatic changes.
4. What is super fluidity?
5. The internal energy of an ideal gas does not change with its volume. Why?
6. State the second law of thermodynamics.
7. Define the molar heat of transformation and give its unit.
8. State Ehrenfest’s classification of phase transitions.
9. Define thermodynamic probability.
10. Classify the following particles according to the statistics they obey:
11. i) electrons     ii) photons  iii) protons and   iv) helium-4.

 

SECTION – B

 

Answer Any FOUR the questions                                                                  (4×7.5=30)

 

11. Obtain the expression for the pressure of an ideal gas, from the kinetic

theory of gases, and hence the ideal equation of state.                                   (5+2.5)

12. Describe Linde’s process for the liquefaction of air.
13. a)What are intensive and extensive variables? Give examples.                            (3)
14. b) Obtain the equation of state for an ideal gas undergoing an adiabatic process. (4.5)
15. Obtain the following expression for the Joule-Kelvin coefficient,.
16. a) Define phase space.                                                                                                 (1.5)
17. b) In how many ways can 3 particles be distributed among 4 states according

to the three statistics.                                                                                         (2+2+2)

SECTION – C

 

Answer Any FOUR questions                                                                             (4×12.5=50)

 

16. a) What is Brownian motion?                                                                                         (2)
17.      b) Discuss the Langevin’s theory of Brownian motion.                                               (10.5)
18. a) Explain Clement and Desormes method for determining.            (9.5)
19. b) Given = 20.3J/mol.-K and R =8.3J/mol.-K, calculate the ratio

of specific  heats.                                                                                                          (3)

18. a) Derive the Clausius-Clayperon equation involving the latent heat.                      (6)
19. b) Derive the Clausius inequality.                      (6.5)
20. a) Obtain the expression for the change in the entropy of an ideal gas.                      (7.5)
21. b) One mole of an ideal gas occupies 10 liters of volume at 4 atm.

The gas is heated at constant volume till its pressure is 8atm. Then it is

allowed to expand at constant pressure. If its final volume is 40 liters,

calculate the change in its entropy.

Given = 3 cal/mol-K and R = 2 cal/mole-K.                                                                  (5)

20. For an ideal Bose gas, obtain the Bose-Einstein distribution for the number of

particles  in each energy level.

 

 

 

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