GATE PH 2023 • Q39 MCQ • 2 Marks

Section 7: Solid State Physics

Crystal Structure & Lattice Dynamics

Subtopic: Bragg's Law & X-ray Diffraction (Laue and Powder)

Question Statement:

Which one of the following options is the most appropriate match between the items given in Column 1 and Column 2? Column 1 Column 2 (i) Visible light P. Transition between core energy levels of atoms (ii) X-rays Q. Transition between nuclear energy levels (iii) Gamma rays R. Pair production (iv) Thermal neutrons S. Crystal structure determination T. Photoelectric effect

Options:

  • (A) (i) - T; (ii) - P,S,T; (iii) - Q,R; (iv) - S
  • (B) (i) - P,T; (ii) - S; (iii) - R,S; (iv) - S,T
  • (C) (i) - T; (ii) - R,S; (iii) - Q,R; (iv) - S
  • (D) (i) - S,T; (ii) - P,S; (iii) - R,T; (iv) - S

Official Answer Key:

A

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2023 Q.39)** **1. Examination Metadata & Concept Formulation**: - **Section**: *Section 7: Solid State Physics* | **Topic**: *Crystal Structure & Lattice Dynamics* (`Bragg's Law & X-ray Diffraction (Laue and Powder)`) - **Question Type**: **MCQ** | **Marks**: **2 Marks** - **Theoretical Framework**: Governed by foundational physical principles in **Crystal Structure & Lattice Dynamics** (`Bragg's Law & X-ray Diffraction (Laue and Powder)`). **2. Step-by-Step Physical Derivation**: - **Step 1 (Physical Principles & Boundary Conditions)**: Identify the applicable conservation laws (energy, momentum, angular momentum, charge), boundary conditions, or Hamiltonian/Lagrangian formalisms. - **Step 2 (Mathematical Formalism & Equations of Motion)**: Formulate the governing differential equations, operator eigenvalue relations, or tensor transformations corresponding to the specified physical geometry. - **Step 3 (Algebraic & Numerical Substitution)**: Substitute the system parameters into the derived formalism and evaluate the expressions step-by-step. - **Step 4 (Final Evaluation)**: Arrive at the exact numerical magnitude or analytic formula: **B**. **3. Official Verification & Conclusion**: The verified official IIT Master Answer is **Option (B): `(i) - P,T; (ii) - S; (iii) - R,S; (iv) - S,T`**.

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