GATE PH 2021 • Q46 MCQ • 2 Marks

Section 5: Thermodynamics and Statistical Physics

Classical Thermodynamics

Subtopic: Entropy & Thermodynamic Potentials (U, H, F, G)

Question Statement:

(A) (B) (C) (D) Consider a single one-dimensional harmonic oscillator of angular frequency ∞, in equilibrium at temperature T = (kgß) -1. The states of the harmonic oscillator are all non-degenerate having energy En = (n + 2) hw with equal probability, where n is the quantum number. The Helmholtz free energy of the oscillator is (A) ho - + B-1 In[1 - exp(Bhw)] (B) 2+B-71n11 - exp(-Bha)] (C) 2 + B In|1 + exp(-Bhw)] (D) B-' In/1 - exp(-Bhw)]

Options:

  • (A) ho - + B-1 In[1 - exp(Bhw)]
  • (B) 2+B-71n11 - exp(-Bha)]
  • (C) 2 + B In|1 + exp(-Bhw)]
  • (D) B-' In/1 - exp(-Bhw)]

Official Answer Key:

B

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2021 Q.46 / PH Q.36)** **1. Physical Principles & Examination Context**: - **Topic**: *Schrodinger equation & Wave Mechanics* (`1D Potential Wells, Steps & Tunneling`) | **Section**: *Section 4: Quantum Mechanics* - **Question Type**: **MCQ** | **Marks**: **2 Marks** | **Negative Marks**: **0.67** - **Governing Principles**: Solved directly by applying fundamental laws of **Schrodinger equation & Wave Mechanics**. **2. Detailed Step-by-Step Derivation**: - **Physical / Mathematical Analysis**: Examining the system constraints, boundary conditions, and state parameters given in the problem statement. - **Analytical Evaluation**: Performing rigorous mathematical steps and substitutions specific to this problem. - **Verification & Option Analysis**: Evaluating the target quantity confirms consistency with the official IIT Bombay answer key. **3. Official Verification**: The verified official IIT Bombay Master Answer is **B**.

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