Subtopic: Wave Mechanics, Operators & Perturbation Theory
Question Statement:
If LL�⃗ is the orbital angular momentum and SS⃗ is the spin angular momentum, then LL�⃗. SS⃗ does NOT
commute with
(A) SSzz (B) LL2 (C) SS2 (D) �LL�⃗ + SS⃗�
2
T
Cp
TTCC
Cp
T TTCC
Cp
T TTCC
Cp
T TTCC
PH 3/10
PH (GATE 2014)
1 PHYSICS-PH
Official Answer Key:
2.5
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE PH 2014 Q.21)**
**1. Theoretical Formulation & Physics Principles**:
This question examines concepts in **Quantum Mechanics** within *Section 4: Quantum Mechanics* (1 Mark, 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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