BPHCT-135 · June 2023 · English
IGNOU BPHCT-135 June 2023 Previous Year Question Paper
THERMAL PHYSICS AND STATISTICAL MECHANICS
Structured previous year question paper for BPHCT-135, June 2023 session.
Max marks: 50 · Questions: 6
Verified: 24 Aug 2026
BACHELOR OF SCIENCE (GENERAL)
(BSCG)
Term-End Examination
June, 2023
BPHCT-135 : THERMAL PHYSICS AND
STATISTICAL MECHANICS
Time : 2 Hours Maximum Marks : 50
Note :
(i) All questions are compulsory. However,
internal choices are given.
(ii) You can use a calculator.
(iii) Symbols have their usual meanings.
(iv) The marks for each question are
indicated against it.
Q1.Attempt any five parts : 2x5=10
(a) Write the van der Waals equation of state for n moles of gas.
(b) Write one example each of a diathermal boundary and adiabatic boundary.
(c) Show Carnot cycle on indicator diagram.
(d) What is Joule-Thomson effect ?
(e) Show graph of spectral energy density of a black body with wavelength at 6000 K.
(f) What is a phase space ? State its significance in statistical mechanics.
(g) B-E and F-D systems are at the same temperature and have same number of particles. Draw B-E and F-D distribution functions versus (¢ — p1)/kgT .
Q2.Answer any two parts: 2x5=10
(a) Discuss Regnault’s experiments on hydrogen, nitrogen and carbon dioxide for 273 K.
(b) Calculate v,,, for oxygen molecules at 300 K. Given : Mo, = 5.31 x 10-8 kg and kp = 1.38 x 10-3 JK“,
(c) Discuss Einstein’s theory of Brownian motion.
Q3.Attempt any two parts: 2x5=10
(a) The pressure inside a tyre is 3 atm. at 300 K. It bursts suddenly. Assuming the change to be adiabatic, calculate the final temperature. Take y =1.4.
(b) Write parametric and exact equations of state for paramagnetic solid and stretched wire.
(c) The coefficient of viscosity of a gas is
Q4.6 x 10-° Nsm~. Calculate the diameter of gas molecular at STP, when average molecular velocity V=4.5x10? ms; number density = 2.7 x10”° molecules m=; and molecular weight of gas = 28. Take Avogadro’s number = 6.023 x 1076 K mol.
Q5.Starting from first law of thermodynamics, derive Mayer's formula : 10 m gram of water at temperature T: is mixed with an equal mass of water of temperature T2. Show that the change in entropy in this process is: As = 2mC in} Tov ) fin) T+T). where T,, = जज is average temperature.
Q6.The thermodynamic probability for a B-E system is given by : 10 we ll (9 iv) ANG; —D! Obtain expression for distribution function. Calculate the Fermi energy for copper, if zs 8.53x 102 electrons cm-°. Also calculate the pressure exerted by electrons in a copper wire. Take the mass of electron as 9.1 x 10-*8g and h = 6.62 x 10°?’ ergs.