(SEM II) THEORY EXAMINATION 2024-25 ENGINEERING PHYSICS

B.Tech (Sem II) Theory Examination 2024–25

Maximum Marks: 70 | Time: 3 Hours

This question paper evaluates a student's understanding of Engineering Physics concepts including relativity, electromagnetic waves, interference, diffraction, lasers, superconductivity, optical fibers, quantum physics, and wave mechanics. The paper is divided into three sections (A, B, and C), testing both conceptual clarity and problem-solving ability.

SECTION A — Short Answer Questions (Q1a–Q1g)

[Total: 14 Marks | 2 Marks Each]

This section checks conceptual fundamentals, formulas, and definitions.

Q1(a)

Meaning of population inversion — a crucial condition for LASER action.

Q1(b)

Definition of Wien’s displacement law — relation between peak wavelength and temperature.

Q1(c)

Definition of dispersive power of grating — ability to separate wavelengths.

Q1(d)

Numerical: Skin depth of an EM wave in copper.
Tests understanding of conductivity, frequency, and penetration depth.

Q1(e)

Expression for de Broglie wavelength of a particle at temperature T.

Q1(f)

Reason why perfect diamagnetism (χ = –1) is essential in superconductors.

Q1(g)

Numerical Aperture (NA) of a silicon optical fiber from core–cladding refractive indices.

This section ensures a strong hold over definitions and small numericals.

SECTION B — Descriptive Questions (Attempt Any 3) (Q2a–Q2e)

[Total: 21 Marks | 7 Each]

This section tests derivations, diagrams, and theoretical explanations.

Q2(a)

Derivation of Maxima & Minima conditions for thin film interference in reflected light.

Q2(b)

Derivation of Maxwell’s equations (Differential Form) — Gauss’s laws, Faraday’s law, Ampere-Maxwell law.

Q2(c)

Construction and working of He-Ne Laser — pumping, population inversion, and transitions.

Q2(d)

Derivation for diameter of dark rings in Newton’s Rings.

Q2(e)

Davisson–Germer experiment: proof of wave nature of electrons.

This section checks derivation skills, clarity of explanations, and conceptual depth.

SECTION C — Long Answer / Numericals (Q3 to Q7)

[Total: 35 Marks | 7 Marks Each | Attempt One Part from Each Question]

This section evaluates advanced understanding with derivations and numericals.

Q3 – Optics & Quantum Physics

Q3(a)

Construction + principle of Optical Fiber,
definitions of:

Acceptance angle

Numerical aperture

Derive relation between acceptance angle and NA.

Q3(b)

Derive Compton wavelength shift
Explain why the effect does not occur in visible light.

Q4 – Lasers / Electromagnetic Theory

Q4(a)

Derive relation between Einstein’s A & B coefficients (stimulated & spontaneous emission).

Q4(b)

State + prove Poynting Theorem, including Poynting vector and energy flow.

Q5 – Diffraction / EM Waves

Q5(a)

Fraunhofer diffraction from a double slit:

Derive conditions for interference & diffraction maxima/minima.

Q5(b)

Derive EM wave equations in vacuum using Maxwell’s equations.
Explain the transverse nature of EM waves.

Q6 – Newton’s Rings | Grating | Particle in Box

Q6(a) (i)

Define Newton’s Rings, explain circular shape, and calculate radius of curvature from given dark ring diameter.

Q6(a) (ii)

Numerical for first-order maximum using a transmission grating.

Q6(b)

Derive normalized wave function and energy eigenvalues for a particle in a 1D box.

Q7 – Superconductivity / Nanomaterials

Q7(a)

Calculate critical field at 5 K using

Hc(T)=H0(1−(TTc)2)H_c(T)=H_0\left(1-\left(\frac{T}{T_c}\right)^2\right)Hc​(T)=H0​(1−(Tc​T​)2)

Also explain Quantum Dot, Quantum Wire, Quantum Well.

Q7(b)

Describe Meissner effect and compare Type I vs Type II superconductors based on magnetic behavior.

WHAT THIS PAPER TESTS

Fundamentals of Electromagnetic Theory
Optics: Diffraction, Interference, Gratings, Optical Fibers
Quantum Mechanics: de-Broglie, Particle-in-a-box, Compton Effect
Lasers & Superconductivity
Derivations + Numericals
Conceptual Clarity + Application