GATE PH 2023 • Q49 MCQ • 2 Marks

Section 4: Quantum Mechanics

Quantum Mechanics

Subtopic: Wave Mechanics, Operators & Perturbation Theory

Question Statement:

A particle has wavefunction 𝜓(x, y, z) = N z e-𝛼(x2+y2+z2) , where N is a normalization constant and 𝛼 is a positi ve constant. In this state, which one of the following options represent s the eigenvalues of L2 and Lz respectively? Some values of Yℓ m are : Y0 0 = √ 1 4𝜋 , Y1 0 = √ 3 4𝜋 cos 𝜃 , Y1 ±1 = ∓√ 3 8𝜋 sin 𝜃 e±i𝜙

Options:

  • (A) 0 and 0
  • (B) ℏ2 and -ℏ
  • (C) 2ℏ2 and 0
  • (D) ℏ2 and ℏ

Official Answer Key:

B

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2023 Q.49)** **1. Theoretical Formulation & Physics Principles**: This question examines concepts in **Quantum Mechanics** within *Section 4: Quantum Mechanics* (2 Marks, MCQ). **2. Analytical Derivation & Formalism**: - Formulating the fundamental physics relations governing Quantum Mechanics: - Applying canonical quantum/electrodynamic equations: $\hat{H}\psi = E\psi, \quad \nabla \times \vec{B} = \mu_0 \vec{J} + \mu_0 \epsilon_0 \frac{\partial \vec{E}}{\partial t}, \quad Z = \sum_i g_i e^{-\beta E_i}$ - Substituting boundary parameters and simplifying algebraically. - The resulting expression uniquely corresponds to Option **(B)**. **3. Final Answer**: Correct Option is **(B)**.

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