GATE PH 2023 • Q61 NAT • 2 Marks

Section 3: Electromagnetic Theory

Electromagnetic Theory

Subtopic: Maxwell's Equations, Waveguides & Radiation

Question Statement:

Consider an electromagnetic wave propagating in the z-direction in vacuum, with the magnetic field given by B⃗ = B⃗ 0ei(kz-𝜔t). If B0 = 10-8 T, the average power passing through a circle of radius 1.0 m placed in the xy plane is P (in Watts). Using 𝜖0 = 10-11 C2 N m2 , what is the value of 103P 𝜋 (rounded off to one decimal place)?

Official Answer Key:

2.5

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2023 Q.61)** **1. Theoretical Formulation & Physics Principles**: This question examines concepts in **Electromagnetic Theory** within *Section 3: Electromagnetic Theory* (2 Marks, NAT). **2. Quantitative Numerical Calculation**: - Identifying known experimental values and physical constants for Electromagnetic Theory. - 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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