GATE PH 2012 • Q47 NAT • 2 Marks

Section 4: Quantum Mechanics

Quantum Mechanics

Subtopic: Wave Mechanics, Operators & Perturbation Theory

Question Statement:

At a certain temperature T, the average speed of nitrogen molecules in air is found to be 400 m/s. The most probable and the root mean square speeds of the molecules are, respectively, (A) 355 m/s, 434 m/s (B) 820 m/s, 917 m/s (C) 152 m/s, 301 m/s (D) 422 m/s, 600 m/s Common Data Questions Common Data for Questions 48 and 49: The wavefunction of a particle moving in free space is given by,

Official Answer Key:

2.5

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2012 Q.47)** **1. Theoretical Formulation & Physics Principles**: This question examines concepts in **Quantum Mechanics** within *Section 4: Quantum Mechanics* (2 Marks, NAT). **2. Quantitative Numerical Calculation**: - Identifying known experimental values and physical constants for Quantum Mechanics. - Setting up the exact evaluation: $\text{Value} = \int \psi^* \hat{\Omega} \psi \, d\tau \quad \text{or} \quad \oint \vec{E} \cdot d\vec{l} = -\frac{\partial \Phi_B}{\partial t}$ - Computing within standard GATE numerical tolerance window. **3. Final Answer**: Official numerical answer is **2.5**.

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