THEORY EXAMINATION (SEM–IV) 2016-17 ELECTRICAL AND ELECTRONICS ENGINEERING MATERIAL

Subject: Electrical and Electronics Engineering Material (EEE403)

Exam Type: Theory
Semester: IV (4th Semester)
Session: 2016–17
Time: 3 Hours
Maximum Marks: 100

Section A – Short Answer Questions (10 × 2 = 20 Marks)

This section tests basic conceptual understanding and definitions related to materials used in electrical and electronic engineering.

Topics covered:

Coordination number: Definition and its importance in crystal structures.

Miller Indices: Finding Miller indices when intercepts are 2a, 3b, and 2c.

Crystalline vs Non-crystalline materials: Difference in atomic arrangement and properties.

Seebeck Effect: Principle of thermoelectric voltage generation.

Superconductivity: Concept and examples of superconducting materials.

Drift vs Diffusion Current: Difference in current flow mechanisms.

Forward-biased P-N Junction: Behavior and current characteristics.

Semiconductor at absolute zero: Explanation of insulating behavior.

Magnetic relation: Relationship between relative permeability and magnetic susceptibility.

Hysteresis Curve: Drawing and explaining for a ferromagnetic material.

Section B – Descriptive Questions (5 × 10 = 50 Marks)

Detailed and numerical questions covering crystal structures, semiconductor theory, and magnetism.

Key questions include:

Basic Definitions:         Unit cell

Space lattice                  Atomic packing factor

Bragg’s Law:

Derivation and use in determining lattice parameters.

Problem: Find interplanar distance (d) for λ = 1.539 Å and θ = 22.5°.

Meissner Effect:

Definition and explanation.   

Distinction between Type I and Type II superconductors with examples.

Heat in a Conductor:

Derivation of expression for heat developed in a current-carrying conductor.

Factors affecting heat generation.

P–N Junction Diode:                  Construction, working, and V–I characteristics.

Classification of Materials:        Distinguish between insulators, conductors, and semiconductors using band theory.

Explain electrical properties of n-type and p-type semiconductors.

Magnetism:    Classification of materials as diamagnetic, paramagnetic, and ferromagnetic.

Explain ferromagnetism in detail.

Magnetostriction:         Definition and types (positive and negative).

Section C – Long Analytical Questions (2 × 15 = 30 Marks)

These involve numerical and detailed conceptual explanations.

Questions include:

Atomic Packing Factor (APF):

Derive APF for:    (i) Simple Cubic (SC)         (ii) Body-Centered Cubic (BCC)      (iii) Face-Centered Cubic (FCC)

Hall Effect in Semiconductor:

Given:

Resistivity ρ=9.23×10−3Ω⋅m\rho = 9.23 × 10^{-3} Ω·mρ=9.23×10−3Ω⋅m

Hall Coefficient RH=3.84×10−4m3C−1R_H = 3.84 × 10^{-4} m^3C^{-1}RH​=3.84×10−4m3C−1

Find: Carrier density and mobility assuming single type of charge carrier.

Magnetic Materials:

Distinguish between soft and hard magnetic materials.

Draw and explain B–H curve for soft magnetic material.

Numerical: Find temperature coefficient of resistance if resistance = 50 Ω at 25°C and 57.2 Ω at 70°C.

Major Topics Covered

Crystal structures and X-ray diffraction               Semiconductor theory and junctions

Superconductivity and Meissner effect               Thermal and electrical properties of conductors

Magnetism (B–H curve, ferromagnetism, magnetostriction)

Hall effect and material characterization

Purpose of the Paper

This exam evaluates the student’s understanding of the physical and electrical properties of materials used in electrical and electronic devices. It focuses on how materials behave under electrical, thermal, and magnetic fields — essential for designing circuits, semiconductors, and electrical systems.