(SEM I) THEORY EXAMINATION 2018-19 PHYSICS

This is a complete AKTU Engineering Physics (KAS101) question paper for B.Tech 1st semester, designed according to the official 100-mark university pattern. The paper covers all the fundamental topics of modern physics, optics, electromagnetic theory, quantum mechanics, lasers, fiber optics, and special relativity.

The paper is divided into three structured sections – A, B, and C, ensuring comprehensive coverage of theory, numericals, conceptual understanding, and derivations.

This question paper is ideal for semester exam preparation, viva practice, assignments, unit revision, and self-study.

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

This section checks understanding of core physics concepts:

Postulates of special theory of relativity

Why nothing can move faster than light

Modification of Ampere’s law & displacement current

Depth of penetration in EM waves

de-Broglie wavelength of photon

Physical significance of wave function ψ

Why two sources cannot be coherent

Resolving power of optical instruments

Spontaneous vs stimulated emission (laser action)

Principle of optical fiber

These are essential 2-mark concepts frequently repeated in exams.

SECTION B – Descriptive Questions (Attempt Any 3 × 10 = 30 Marks)

This section includes derivations, explanations, and quantum concepts:

Special Relativity

Relativistic velocity addition theorem

Consistency with Einstein’s postulates

Maxwell’s Equations

Integral & differential forms

Physical meaning of each equation

Speed of EM waves c=1μ0ϵ0c = \frac{1}{\sqrt{\mu_0 \epsilon_0}}c=μ0​ϵ0​​1​

Quantum Mechanics

Time-independent and time-dependent Schrödinger equations

Fraunhofer Diffraction (Single Slit)

Formation of maxima and minima

Relative intensity distribution

Optical Fibers

Structure, types (step-index, graded-index, multimode, single-mode)

Advantages & disadvantages

This section strengthens conceptual clarity and derivation skills.

SECTION C – Long Questions (Attempt Any 2 from Each Set) (5 × 2 = 10 Marks per section)

Q3 – Relativity

Choose any 2:

Length contraction derivation

Apparent volume of a moving cube

Variation of mass with velocity

These are the core formulas of special relativity.

Q4 – Electromagnetic Waves

Choose any 2:

Poynting vector & Poynting theorem

Coulomb’s law derived from Maxwell’s first equation

Magnitude of solar Poynting vector using Sun’s power and radius

These questions test EM wave theory and vector calculus.

Q5 – Quantum Mechanics

Choose any 2:

Particle in a 1D box: eigenvalues and normalized wave function

Compton effect and Compton shift derivation

Proof that the given function represents a stationary state

This section covers the most important quantum physics topics.

Q6 – Interference & Diffraction

Choose any 2:

Newton's rings formation + formula for dark ring diameters

Thin wedge film → calculate angle of wedge

Overlapping of spectral lines in diffraction grating

Optics questions common in AKTU exams.

Q7 – Lasers & Fiber Optics

Choose any 2:

Construction & working of Ruby Laser

Population ratio in He-Ne laser

Numerical aperture, acceptance angle, critical angle of a fiber

These questions cover laser physics & fiber communication.