(Semester-I) Theory Examination 2017 - 18 ENGINEERING PHYSICS-I

This Engineering Physics question paper is designed to assess a student’s understanding of Relativity, Quantum Mechanics, Electromagnetic Theory, Lasers, Interference, Diffraction, Thin Films, Polarization, and Optical Fiber Communication. The paper is divided into three major sections: A, B, and C, each focusing on different levels of conceptual depth—from basic definitions to advanced derivations and numerical applications.

SECTION A – Short Conceptual Questions (Q1a–Q1g)

Total Marks: 14 (2 marks × 7 questions)
Section A tests foundational knowledge and clarity of basic concepts that form the backbone of engineering physics.

Q1(a)

Is Earth an inertial or non-inertial frame? Justification required.
→ Tests understanding of reference frames and Newton’s laws.

Q1(b)

Wien’s displacement law.
→ Checks understanding of blackbody radiation and temperature–wavelength relation.

Q1(c)

Group velocity.
→ Conceptual understanding of wave packets and energy propagation.

Q1(d)

Dispersive power of a plane transmission grating.
→ Tests optics and diffraction fundamentals.

Q1(e)

Difference between spontaneous and stimulated emission.
→ Core concept for lasers and quantum transitions.

Q1(f)

Specific rotation.
→ Concept used in optical activity and polarimetry.

Q1(g)

Acceptance angle of optical fiber.
→ Key parameter in fiber optics determining light-guiding capability.

This section ensures students are comfortable with definitions, physical meaning, and basic scientific laws.

SECTION B – Descriptive & Derivational Questions (Q2a–Q2e)

Total Marks: 21 (Attempt any 3 × 7 marks)
This section evaluates a student’s analytical ability, derivation skills, and conceptual explanations.

Q2(a) – Galilean Transformation & Invariance

Derive Galilean transformation and prove that length and acceleration remain invariant under these transformations.

Q2(b) – Planck’s Radiation Law

Complete derivation with explanation of why Planck’s law is valid for all wavelengths.

Q2(c) – Plane Transmission Grating

Construction, theory, and spectral formation—important for diffraction and resolving power.

Q2(d) – Ruby Laser & Four-Level Advantage

Compares three-level and four-level lasers; explains ruby laser construction and population inversion.

Q2(e) – Holography

Covers principle, formation of hologram, reconstruction, and uniqueness of holography.

This section targets higher-order thinking and understanding of physical processes.

SECTION C – Long Answer Questions (Q3–Q7)

Each question carries 7 marks; attempt any one part from each.
These questions require deep conceptual understanding, mathematical derivations, and numerical accuracy.

Q3 – Relativity Concepts

Q3(a)

Relativistic velocity addition theorem + consistency with Einstein’s postulate.
→ A major derivation in Special Relativity.

Q3(b)

Time dilation, derivation, and a numerical question to find the speed at which a clock loses 1 minute per hour.
→ Tests real-world application of relativity.

Q4 – Quantum Mechanics

Q4(a)

Davisson–Germer experiment → proof of wave nature of electrons.
→ Fundamental experimental validation of de-Broglie waves.

Q4(b)

Energy states for particle in 1-D box + probability calculation for ground state.
→ Involves quantization and probability distribution.

Q5 – Interference & Diffraction

Q5(a)

Interference due to wedge-shaped thin film → derivation for fringe width.
→ Important for understanding thin film patterns.

Q5(b)

Fraunhofer diffraction at a single slit → derive intensity formula + numerical.
→ Tests ability to interpret diffraction patterns.

Q6 – Polarization & Optical Activity

Q6(a)

Double refraction + calculation of quarter-wave plate thickness for quartz.
→ Focuses on birefringence and phase retardation.

Q6(b)

Optical activity + Fresnel’s theory + derivation of rotation angle.
→ Strong conceptual + mathematical question.

Q7 – Optical Fiber Communication

Q7(a)

Difference between single-mode and multimode fibers, with characteristics.
→ Important for communication engineering.

Q7(b)

Dispersion, attenuation, and calculation of fiber loss in dB/km.
→ Tests numerical and conceptual understanding.