BPHCT-135 IGNOU Solved Assignment 2026-27

BPHCT-135 Solved Assignment: Thermal Physics and Statistical Mechanics (TMA)

This structured digital PDF solution adheres to the IGNOU Bachelor of Science (Multidisciplinary) curriculum, covering Block-1 to Block-4 of BPHCT-135: Thermal Physics and Statistical Mechanics. Each unit includes verified answers for theoretical questions, numerical problems, and short-answer formats, strictly within word limits (500/250/100 words). Solutions are cross-referenced with the official eGyanKosh syllabus for accuracy.

Key Syllabus Units Covered

• Block-1: Kinetic Theory of Gases
  • Derivation of pressure, temperature, and internal energy from kinetic theory assumptions.
  • Maxwell-Boltzmann distribution of molecular speeds with solved numerical examples.
  • Ideal gas law and deviations: Van der Waals equation with critical constants.
• Block-2: Zeroth and First Laws of Thermodynamics
  • Statement and mathematical formulation of the Zeroth Law (thermal equilibrium).
  • First Law of Thermodynamics: Work, heat, and internal energy changes for adiabatic/isentropic processes.
  • Thermodynamic potentials (Helmholtz, Gibbs) with applications to phase transitions.
• Block-3: Second and Third Laws of Thermodynamics
  • Carnot cycle efficiency and Kelvin-Planck statement of the Second Law.
  • Entropy calculations for reversible/irreversible processes (e.g., mixing gases).
  • Third Law: Nernst heat theorem and absolute entropy determination.
• Block-4: Statistical Mechanics
  • Microcanonical, canonical, and grand canonical ensembles with partition function derivations.
  • Fermi-Dirac and Bose-Einstein statistics for quantum gases (applied to electrons/photons).
  • Boltzmann distribution and its connection to classical thermodynamics.

Sample Problem Solutions

Q1 (Block-1): Derive the expression for the root mean square (RMS) speed of gas molecules using kinetic theory. Given N molecules with masses m and average kinetic energy ⟨KE⟩, show that v_rms = √(3⟨KE⟩/m).

Solution:

• Assume molecules move randomly in 3D space with velocities v_x, v_y, v_z.
• RMS speed v_rms = √[(v_x² + v_y² + v_z²)/3].
• From kinetic theory, ⟨KE⟩ = (1/2)m(v_x² + v_y² + v_z²).
• Substitute and simplify to obtain v_rms = √(3⟨KE⟩/m).

FAQs

• Q: Are solutions provided in both English and Hindi?

  Yes. The TMA solutions include translated answers in Hindi for questions requiring Hindi medium submission, while core derivations and numericals remain in English for clarity.

• Q: How do I ensure my submission meets IGNOU’s word limits?

  Each question is solved within the strict word limits (500/250/100 words) as per the current academic session’s guidelines. The PDF includes highlighted word counts for quick verification.

Submission Deadlines & Format

Adhere to the IGNOU TMA submission window (typically June/December sessions). Submit as a single PDF file with:

• Student ID, name, and enrollment number.
• Course code BPHCT-135 and assignment number.
• Page numbers and question-wise separation.

Note: Late submissions incur penalties; verify deadlines via official IGNOU portals.