BPHCT-135 · December 2024 · English
IGNOU BPHCT-135 December 2024 Previous Year Question Paper
THERMAL PHYSICS AND STATISTICAL MECHANICS
Structured previous year question paper for BPHCT-135, December 2024 session.
Max marks: 50 · Questions: 5
Verified: 24 Aug 2026
BACHELOR OF SCIENCE
(GENERAL)
(BSCG)
Term-End Examination
December, 2024
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 : 5x2=10
(a) Define the degree of freedom of a molecule and write its mathematical expression.
(b) Draw the Maxwell distribution curve vs. speed for any three temperatures T1, Tz, Ts such that Ti > Tz > Ts.
(c) Write down the differential form of the first law of thermodynamics.
(d) Draw isobaric and isochoric processes in a P-V diagram.
(e) Draw the phase diagram of water.
(f) Define the spectral energy density for a blackbody radiation.
(g) State any two assumptions for the Maxwell-Boltzmann statistics.
(h) Explain what are the microstates and macrostates of a thermodynamic system.
Q2.Answer any two parts: 2x5=10
(a) Obtain an _ expression for mean translational energy per degree of freedom for molecules of a Maxwellian gas. 5
(b) What is Brownian motion ? State its observed characteristics. 1+4
(c) Define mean free path and obtain an expression for it in zeroth approximation.
Q3.Answer any two parts : 2x5=10
(a) What do you understand by the term thermodynamic system ? How do you classify boundaries to determine the nature of a system ? 5
(b) Obtain the following expressions for isothermal compressibility and volume expansion coefficient : 5 1/0 By =2 oP and a =-— Pe p\ dE )p p\ eT }p
(c) Show that for an ideal gas, the difference in heat capacities at constant pressure and at constant volume is equal to R.
Q4.Answer any two parts: 2x5=10
(a) Depict Carnot cycle on P-V diagram and obtain the expression for efficiency of a Carnot engine. 1+4
(0) Define entropy. Obtain the expression for change in entropy of a gas when it undergoes an isothermal change. 1+4
(c) Write Maxwell’s relations and show that for a van der Waals’ gas : 243 OV), V2
Q5.Answer any one part : 1x10=10
(a) Obtain an expression for the single particle partition function of a monoatomic ideal gas. 10
(b) Starting from the expression : w-T]—2_N:! i (si-Ni) ¢ obtain the expression for Fermi-Dirac distribution function. Plot it vs. energy of different temperatures. 8+2 (Hast we aa adit है ? sam Gf