Subtopic: Wave Propagation in Dielectrics & Conductors
Question Statement:
(A)
(B)
(C)
Choose the correct statement from the following.
Silicon is a direct band gap semiconductor.
Conductivity of metals decreases with increase in temperature.
Conductivity of semiconductors decreases with increase in temperature.
(D) Gallium Arsenide is an indirect band gap semiconductor.
Options:
(A)
(B)
(C) Choose the correct statement from the following. Silicon is a direct band gap semiconductor. Conductivity of metals decreases with increase in temperature. Conductivity of semiconductors decreases with increase in temperature.
(D) Gallium Arsenide is an indirect band gap semiconductor.
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE PH 2021 Q.19 / PH Q.9)**
**1. Physical Principles & Examination Context**:
- **Topic**: *Electromagnetic Waves in Media* (`Wave Propagation in Dielectrics & Conductors`) | **Section**: *Section 3: Electromagnetic Theory*
- **Question Type**: **MCQ** | **Marks**: **1 Mark** | **Negative Marks**: **0.33**
- **Governing Principles**: Solved directly by applying fundamental laws of **Electromagnetic Waves in Media**.
**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 **B**.
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