(SEM VIII) THEORY EXAMINATION 2017-18 ELECTRICAL ELECTRONICS ENGINEERING MATERIAL

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ELECTRICAL & ELECTRONICS ENGINEERING MATERIAL (NEE-801)

According to the uploaded question paper

The Electrical & Electronics Engineering Material examination is divided into three sections: A, B, and C. The paper focuses on crystal structure, semiconductor physics, magnetic materials, superconductivity, and electronic device fundamentals.

Below is a detailed explanation of each section in descriptive format.

Section A – Fundamental Concepts of Engineering Materials (20 Marks)

Section A consists of ten compulsory short-answer questions, each carrying two marks. This section tests your understanding of basic crystallography, solid-state physics, thermoelectric effects, superconductivity, and magnetic properties.

The questions include differences between primitive cell and unit cell, definition of Miller indices, space lattice and coordination number, proof of interplanar spacing ratio in simple cubic system, energy band and forbidden band concepts, Seebeck and Peltier effects, superconducting critical temperature calculation, magnetostriction, and drift and continuity equations.

This section mainly checks your clarity of fundamental solid-state physics concepts. For example, energy band theory explains why materials behave as conductors, semiconductors, or insulators. The Seebeck effect explains generation of emf due to temperature difference, while Peltier effect explains heating or cooling at junctions.

The superconductivity numerical problem requires applying the relation between magnetic field and temperature below critical temperature.

Although short, this section forms the foundation for deeper derivations in later sections.

Section B – Theory, Derivations, and Device Principles (30 Marks)

Section B requires you to attempt any three questions, each carrying ten marks. This section evaluates theoretical derivations and practical understanding of material behavior.

Topics include Bragg’s Law with numerical calculation of lattice parameter, Langevin’s theory of diamagnetism or paramagnetism, working principle and types of MOSFET, derivation of intrinsic semiconductor conductivity expression, and zone theory of solids.

For example, Bragg’s Law relates wavelength, interplanar spacing, and diffraction angle as:

nλ = 2d sinθ

Using this relation, the lattice parameter of a cubic crystal can be calculated.

The MOSFET question requires explaining structure, operation in enhancement and depletion modes, and differences between n-channel and p-channel devices.

The intrinsic conductivity derivation requires showing that conductivity depends on carrier concentration and mobility of electrons and holes.

This section tests your understanding of semiconductor devices and magnetic theory.

Section C – Advanced Derivations and Numerical Applications (50 Marks)

Section C carries the highest weightage and requires you to attempt one part from each question. This section focuses on detailed derivations, advanced material properties, and numerical problem-solving.

Topics include derivation of Hall coefficient expression, Hall effect numerical calculation of carrier density and mobility, resistivity expression of metals, B-H hysteresis loop sketch, relation between relative permeability and susceptibility, X-ray diffraction calculation, ferrites and ferrimagnetism, hysteresis and eddy current losses, superconductivity with Meissner effect, and thermal conductivity derivation.

For example:

The Hall effect derivation requires showing that Hall coefficient RH = –1/(ne) for single carrier conduction.

The resistivity derivation uses free electron theory and shows ρ = m/(ne²τ).

The Meissner effect explains expulsion of magnetic flux below critical temperature.

Thermal conductivity derivation relates heat flow to temperature gradient using Fourier’s law.

This section tests deep understanding of electromagnetic theory, solid-state physics, and transport phenomena.