GATE PH 2021 • Q38 MCQ • 2 Marks

Section 1: Mathematical Physics

Fourier and Laplace transforms

Subtopic: Fourier Series & Integral Transforms

Question Statement:

Consider a spinS - /z particle in the state lp) - 117 . The probability that a measurement finds the state with Sx = +h/2 is (A) | 5/18 (B) | 11/18 (C) | 15/18 (D) 17/18

Options:

  • (A) | 5/18
  • (B) | 11/18
  • (C) | 15/18
  • (D) 17/18

Official Answer Key:

D

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2021 Q.38 / PH Q.28)** **1. Physical Principles & Examination Context**: - **Topic**: *Fourier and Laplace transforms* (`Fourier Series & Integral Transforms`) | **Section**: *Section 1: Mathematical Physics* - **Question Type**: **MCQ** | **Marks**: **2 Marks** | **Negative Marks**: **0.67** - **Governing Principles**: Solved directly by applying fundamental laws of **Fourier and Laplace transforms**. **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 **D**.

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