GATE PH 2018 â€Ē Q4 NAT â€Ē 1 Mark

General Aptitude

Quantitative & Analytical Aptitude

Subtopic: Analytical Reasoning

Question Statement:

In spherical polar coordinates (r, 𝜃, 𝜙), the unit vector ðœƒĖ‚ at (10, 𝜋/4, 𝜋/2) is (A) kĖ‚ (B) 1 √2 (jĖ‚ + kĖ‚) (C) 1 √2 (-jĖ‚ + kĖ‚) (D) 1 √2 (jĖ‚ - kĖ‚) 2/12

Official Answer Key:

2.5

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2018 Q.4)** **1. Theoretical Formulation & Physics Principles**: This question examines concepts in **Quantitative & Analytical Aptitude** within *General Aptitude* (1 Mark, NAT). **2. Quantitative Numerical Calculation**: - Identifying known experimental values and physical constants for Quantitative & Analytical Aptitude. - 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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