About this previous year paper
This is the complete B.Tech 1st Semester Engineering Physics (KAS101) question paper structured exactly as per the official 100-mark university exam pattern. It covers the full syllabus including Special Theory of Relativity, Electromagnetic Waves, Wave Optics, Quantum Mechanics, Lasers, Fiber Optics, Interference, Diffraction, and Photon Theory of Light.
This question paper is extremely useful for students preparing for semester exams, viva, and numerical practice, as it includes conceptual questions, derivations, numericals, and application-based physics problems.
SECTION A – Short Concept Questions (10 × 2 = 20 marks)
This section checks understanding of fundamental physics concepts:
Inertial vs non-inertial frames of reference
Why aircraft in steady flight is considered almost inertial
Massless particles, speed of light, and relation E = pc
Bohr’s quantization rule via de-Broglie matter waves
Dispersive power of transmission grating
Negligible modal dispersion in single-mode fibers
Wave impedance
Electromagnetic vs matter waves
Why independent sources do not interfere
Population inversion, laser basics, and energy relations
This part helps with fast revision of key definitions and reasoning concepts.
SECTION B – Descriptive Questions (Attempt Any 3 × 10 = 30 marks)
This section includes concept-based explanations and numerical problems:
Population inversion and comparison of He-Ne laser with Ruby laser
Time dilation problem involving round-trip space travel
Electric and magnetic field amplitudes using solar constant
De Broglie wavelength calculation
Resolving power of a diffraction grating and minimum resolvable wavelength
Relative population of laser states using Boltzmann distribution
These questions strengthen numerical ability and conceptual clarity.
SECTION C – Long Answer Questions (5 × 10 = 50 marks)
Students must attempt one part from each question. These include major derivations and advanced theory topics.
Q3 – Special Theory of Relativity
Postulates of relativity + derivation of Lorentz transformations + length contraction
OR
Einstein’s mass–energy relation and derivation of relativistic kinetic energy
Q4 – Electromagnetism
Maxwell’s equations in free space + displacement current + modification of Ampere’s law
OR
Poynting theorem and energy flow in EM fields
Q5 – Quantum Mechanics & Compton Effect
Schrödinger equation for a particle in 1-D box → eigenvalue & eigenfunction
OR
Compton effect and proof of photon nature of light
Q6 – Wave Optics
Formation of Newton’s rings + bright and dark ring conditions
OR
Fraunhofer diffraction at single slit + intensity of first subsidiary maximum ≈ 4.5%
Q7 – Fiber Optics & Lasers
Acceptance angle, acceptance cone, numerical aperture
OR
Ruby laser construction, working, and labeled diagram
These questions cover high-weightage derivations required to score full marks.