(SEM II) THEORY EXAMINATION 2018-19 PHYSICS

This document contains the complete and authentic B.Tech (Semester II) PHYSICS Theory Examination Question Paper for the academic session 2018–19, Subject Code KAS201, Total Marks 100, Time 3 Hours.
It is structured to test a student's understanding of engineering physics, including modern physics, optics, lasers, electromagnetic theory, relativity, and quantum mechanics.

The examination is divided into three major sections, each designed to evaluate conceptual clarity, analytical skills, numerical problem-solving, and the ability to apply physics principles to practical scenarios.

SECTION A — Short Conceptual Questions (2 × 10 = 20 Marks)

This section contains 10 brief questions covering fundamental physics concepts.
Students must demonstrate basic understanding of:

Negative outcome of Michelson–Morley experiment

Concept of length contraction in relativity

Inertial vs non-inertial frames of reference

Nature and properties of massless particles

Definition of displacement current

Meaning of Poynting vector and Poynting theorem

Assumptions in Planck’s quantum hypothesis

Necessity of extended sources in interference

Formation of Newton’s rings

Definition of dispersive power of diffraction grating

These questions test the student’s foundational knowledge across modern physics, optics, and electromagnetics.

SECTION B — Analytical & Descriptive Questions (Any 3 × 10 = 30 Marks)

This section evaluates deeper understanding through detailed explanations, derivations, and numerical calculations.
Topics include:

1. Special Theory of Relativity

Derivation of time dilation

Numerical question involving moving clock losing 30s in 24 hours

2. Interference in Thin Films

Conditions for maxima/minima

Complementary nature of reflected vs transmitted light patterns

3. LASER Physics

Working of 3-level and 4-level laser systems

Advantages of 4-level LASER over 3-level

4. Optical Fibers

Definition & classification

Calculations of:

Numerical aperture (NA)

Acceptance angle

Critical angle

5. Electromagnetic Theory

Continuity equation + significance

Calculation of E-field & B-field at a distance from a lamp

This section emphasizes problem-solving and application of physics laws.

SECTION C — Long Answer / Application-Based Questions (40 Marks)

Each subsection contains two questions, from which the student attempts one.

Part 3 — Relativity / Diffraction

Derivation of Einstein’s mass–energy relation, E = mc²

Numerical question on relativistic mass, momentum, energy
OR

Fraunhofer diffraction at a single slit + intensity distribution

Part 4 — EM Waves / LASER

Proof that electromagnetic waves are transverse

Numerical problems on conduction & displacement current
OR

Ruby Laser construction & energy calculation

Part 5 — Quantum Theory / Maxwell’s Equations

Derivation of Planck’s radiation law

Applications: Wien’s law and Rayleigh-Jeans law
OR

Maxwell’s equations & modification of Ampere’s law

Part 6 — EM Radiation Pressure / Compton Effect

Derivation of radiation momentum and pressure
OR

Full derivation of Compton shift with numerical calculation

Part 7 — Quantum Mechanics / Grating

Derivation of Schrödinger’s equations
OR

Diffraction grating, missing orders & angular separation calculation

These questions test advanced reasoning, detailed derivations, and numerical analysis.

SAMPLE QUESTIONS FROM THE PAPER

To illustrate the depth of the exam, here are two sample questions included in the document:

Example 1 (Section A):

What is displacement current?
— Tests basic electromagnetic theory.

Example 2 (Section C):

Deduce Einstein’s mass–energy relation E = mc².
— Tests deep conceptual understanding of relativity.

Overall Coverage of the Question Paper

This question paper thoroughly covers core areas of physics required for engineering students:

Modern Physics & Relativity

Length contraction, time dilation

Mass–energy equivalence

Michelson–Morley experiment

Electromagnetic Theory

Maxwell’s equations

Displacement current

EM wave properties (E & B field calculations)

Optics

Newton’s rings

Diffraction (Fraunhofer)

Interference in thin films

Grating spectra

Quantum Mechanics

Schrödinger equations

Planck’s radiation law

Compton effect

Laser & Fiber Optics

Ruby laser, 3-level & 4-level lasers

Optical fibers: NA, critical angle, acceptance angle

Wave Physics

Radiation pressure

Momentum of EM waves

The paper checks both theoretical understanding and numerical competence, making it a complete assessment tool for first-year engineering physics.