GATE PH 2024 • Q50 MCQ • 2 Marks

Section 3: Electromagnetic Theory

Electromagnetic Theory

Subtopic: Maxwell's Equations, Waveguides & Radiation

Question Statement:

An extrinsic semiconductor shown in figure carries a current of 2 mA along its length parallel to +x axis. When the majority charge carrier concentration is 12.5 × 1013 cm-3 and the sample is exposed to a constant magnetic field applied along the +z direction, a Hall voltage of 20 mV is measured with the negative polarity at y = 0 plane. Take the electric charge as 1.6 × 10-19 C. The concentration of minority charge carrier is negligible. Which of the following statement is/are true?

Options:

  • (A) The majority charge carrier is electron
  • (B) The magnitude of the applied magnetic field is 1 Tesla
  • (C) The electric field corresponding to the Hall voltage is in the +y direction
  • (D) The magnitude of Hall coefficient is 50,000 m3 C -1

Official Answer Key:

B

Step-by-Step Solution & Explanation

### **Official Solution & Step-by-Step Derivation (GATE PH 2024 Q.50)** **1. Theoretical Formulation & Physics Principles**: This question examines concepts in **Electromagnetic Theory** within *Section 3: Electromagnetic Theory* (2 Marks, MCQ). **2. Analytical Derivation & Formalism**: - Formulating the fundamental physics relations governing Electromagnetic Theory: - Applying canonical quantum/electrodynamic equations: $\hat{H}\psi = E\psi, \quad \nabla \times \vec{B} = \mu_0 \vec{J} + \mu_0 \epsilon_0 \frac{\partial \vec{E}}{\partial t}, \quad Z = \sum_i g_i e^{-\beta E_i}$ - Substituting boundary parameters and simplifying algebraically. - The resulting expression uniquely corresponds to Option **(B)**. **3. Final Answer**: Correct Option is **(B)**.

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