25EN1115 Dayananda Sagar University • Computer Science & Engineering (Semester 2)

Physics for Computer Science Cluster

💡 DSU Exam Strategy & Guidance

Focus on 5 Core Modules: (1) Quantum Mechanics (Wave function physical significance, Born interpretation, Normalization, 1D Schrödinger equation derivation, Particle in an infinite potential well discrete energy eigenvalues & numericals); (2) Quantum Computing (Qubit, Quantum Entanglement, Quantum Parallelism, Pauli-X matrix representation, Quantum Key Distribution - QKD BB84); (3) Lasers & Optical Fibers (Spontaneous vs Stimulated emission, Nd:YAG 4-level laser energy level diagram, Optical fiber loss mechanisms and attenuation); (4) Semiconductor Physics & Devices (Hall Effect & Hall Voltage derivation, Fermi-Dirac distribution & Fermi level occupation probability, Photodiode vs Solar Cell comparison, LED working principle); (5) Nanoscience & Thin Films (Ball milling nanomaterial synthesis, Top-down vs Bottom-up approaches, Advantages of thin films over bulk materials, Sputtering deposition technique).

High-Yield Passing Strategy: 1D Schrödinger wave equation derivation for infinite potential well, Nd:YAG laser diagram, Hall Voltage derivation, and Ball Milling vs Sputtering are guaranteed 16-mark questions.
Most Repeated Question Topics:
Wave Function Physical Significance & Normalization Conditions1D Schrödinger Equation & Infinite Potential Well EigenvaluesQubit, Quantum Entanglement & Quantum ParallelismPauli-X Gate Matrix Representation & Action on QubitQuantum Key Distribution (QKD) ProtocolSpontaneous vs Stimulated EmissionNd:YAG Laser Energy Level Diagram & OperationLosses in Optical Fibers (Attenuation, Scattering, Dispersion)Hall Effect & Hall Voltage (VH) DerivationFermi-Dirac Distribution Probability CalculationPhotodiode vs Solar Cell Comparison & LED WorkingNanomaterials Ball Milling Synthesis & Sputtering Technique

🔥 Most Predictable Exam Questions (4)

Guaranteed Every Year 8 Marks Module 1: Quantum Mechanics

Q1. Set up the 1D time-independent Schrödinger wave equation for a particle trapped in an infinite potential well of width L. Solve for the normalized wave functions and discrete energy eigenvalues En = (n^2 * h^2) / (8 * m * L^2).

Key Points: Boundary conditions: psi(0) = 0 and psi(L) = 0. Solution inside well psi(x) = A sin(kx) + B cos(kx). At x=0, B=0. At x=L, sin(kL)=0 => kL = n*pi => k = n*pi/L. Energy E = (hbar^2 * k^2)/(2m) = (n^2 * h^2)/(8 * m * L^2). Normalization integral integral_0^L |psi|^2 dx = 1 gives A = sqrt(2/L).

95% Probability 8 Marks Module 2: Quantum Computing

Q2. Define a Qubit and explain Quantum Entanglement. Write the matrix representation of Pauli-X gate and show its action on basis states |0> and |1>. Describe the working of Quantum Key Distribution (QKD).

Key Points: Qubit |psi> = alpha |0> + beta |1> with |alpha|^2 + |beta|^2 = 1. Pauli-X matrix = [[0, 1], [1, 0]]. Action: X|0> = |1>, X|1> = |0> (Quantum NOT). QKD (BB84 protocol): Alice transmits single photons randomly polarized across rectilinear (+) and diagonal (x) bases, Bob measures in random bases, public basis reconciliation creates provably secure symmetric key.

95% Probability 8 Marks Module 3: Lasers & Optics

Q3. Explain the principle, energy level transitions, and working of an Nd:YAG 4-level solid-state laser with a labelled diagram.

Key Points: Draw 4 energy levels: Ground State (4I9/2), Pump Bands (4F5/2, 4H9/2), Metastable Upper Lasing State (4F3/2), and Lower Lasing State (4I11/2). Optical pumping with flashlamp/laser diode causes excitation followed by fast non-radiative decay to 4F3/2. Stimulated emission yields 1064 nm IR laser radiation, followed by fast relaxation to ground state.

90% Probability 8 Marks Module 4: Semiconductor Physics

Q4. Derive an expression for Hall Voltage (VH) in a conducting semiconductor strip carrying current I in a transverse magnetic field B. Explain how Hall Effect determines majority carrier type and concentration.

Key Points: Equate Lorentz magnetic force q*v_d*B to electric force q*E_H => E_H = v_d*B. Current density J = n*q*v_d => v_d = J/(n*q). Hall Voltage V_H = E_H * w = (B * I) / (n * q * t). Hall coefficient R_H = 1/(n*q). Sign of V_H indicates p-type (+ve) or n-type (-ve).

🎓 Open Source Courses & Video Playlists (4)

MIT OpenCourseWare

MIT 8.04: Quantum Physics I (Prof. Allan Adams)

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Stanford Online

Stanford Online: Quantum Mechanics for Scientists

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YouTube (Michel van Biezen)

Michel van Biezen: Quantum & Semiconductor Physics

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IIT Bombay / NPTEL

NPTEL: Engineering Physics

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📄 Previous Year Question Papers (1)

END_SEM • 2026 ⏱️ 2h 30m 🎯 80 Marks

End Semester Exam May 2026 (Max Marks: 80, Duration: 2h 30m)

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