00 ECE 2105 Term Final Exam Strategy & Question Prediction Guide
Overview
Strategic exam guide for ECE 2105: Electromagnetic Fields and Waves based on 11 years of past university question papers (2015–2025). Provides paper architecture rules, high-yield topic predictions, mark-scoring guidelines, and an effort-vs-reward filter for securing an A+ grade.
1. Exam Paper Architecture & Rules
- Total Marks: 210 Marks (35 Marks per Question 6 Questions).
- Time Duration: 3 Hours (180 Minutes ⟹ 30 minutes per 35-mark question).
- Sectional Split:
- Section A (Instructor 1 - Mashuk Sir): Questions 1 to 4 (Answer any 3 out of 4). Covers Vector Calculus, Electrostatics, Maxwell’s Equations, EM Waves.
- Section B (Instructor 2 - Sanglap Sir / Naymur Rahman Sir): Questions 5 to 8 (Answer any 3 out of 4). Covers Magnetostatics, Magnetic Boundary Conditions, Wave Parameters, Radio Propagation.
2. Predicted Question Types & Exam Predictions
🏛 Section A: Instructor 1 (Mashuk Sir)
Question 1: Vector Calculus & Electrostatic Postulates (35 Marks) [100% Probability]
- Part (a) [10M]: Vector Identity Proofs: ∇ (∇V) ≡ 0 or ∇ · (∇ A) ≡ 0
[PYQ: 2016, 2018, 2021]. - Part (b) [12M]: Fundamental Postulates of Electrostatics (Differential/Integral) + Conversion Proofs using Divergence/Stokes’s Theorems
[PYQ: 2015, 2017, 2020, 2022]. - Part (c) [13M]: Inadequacy of Circuit Theory under High-Frequency Conditions (d ≥ λ)
[PYQ: 2018, 2019, 2020, 2021].
Question 2: Gauss’s Law & Electric Dipole (35 Marks) [100% Probability]
- Part (a) [15M]: Uniform Spherical Charge Cloud Derivation (r<a: E ∝ r; r>a: E ∝ 1/r^2)
[PYQ: Heavily Tested: 2018, 2019, 2020, 2022]. - Part (b) [15M]: Electric Dipole Potential V = p cosθ / (4πε₀ r^2) and Field E Derivations using Binomial Series Expansion
[PYQ: Heavily Tested: 2016, 2017, 2019, 2021, 2023, 2024]. - Part (c) [5M]: 2D Field & Equipotential Sketches for Negative Charge Cloud or Dipole
[PYQ: 2024, 2025].
Question 3: Dielectric Polarization & Boundary Conditions (35 Marks) [100% Probability]
- Part (a) [12M]: Bound Charge Densities Derivation (ρps = P · an, ρp = -∇ · P) & Proof of D = ε₀ E + P
[PYQ: 2016, 2019, 2021]. - Part (b) [13M]: Dielectric-Dielectric Boundary Conditions (E1t = E2t, D1n - D2n = ρs) & Dielectric Refraction Law tanα1 / tanα2 = ε1 / ε2
[PYQ: 2015, 2017, 2022, 2025]. - Part (c) [10M]: Solved PYQ Numerical on Dielectric Boundary Refraction or Spherical Cloud Field
[PYQ: 2017, 2021, 2025].
Question 4: Maxwell’s Equations & Poynting Theorem (35 Marks) [100% Probability]
- Part (a) [12M]: Maxwell’s Displacement Current Masterstroke (Jd = ∂D/∂t) Derivation from Ampere’s Law & Continuity
[PYQ: Heavily Tested: 2015, 2018, 2020, 2022]. - Part (b) [13M]: Complete 4 Maxwell’s Equations Table (Differential & Integral Forms) + Physical Interpretations
[PYQ: 2015–2025]. - Part (c) [10M]: Poynting’s Theorem Power Flow Proof (-∇ · S = J · E + ∂w/∂t)
[PYQ: 2016, 2019, 2022, 2025].
🏛 Section B: Instructor 2 (Sanglap Sir / Naymur Rahman Sir)
Question 5: Magnetostatic Postulates & Biot-Savart Law (35 Marks) [100% Probability]
- Part (a) [10M]: Magnetostatic Postulates (∇ · B = 0, ∇ H = J) + Lorentz Force F = q(E + u B)
[PYQ: 2015, 2018, 2021]. - Part (b) [15M]: Biot-Savart Law Application: Magnetic Field of Finite Straight Wire (2L) B = aϕ μ₀ I L / (2π r √(r^2 + L^2)) & Infinite Wire Limit
[PYQ: Heavily Tested: 2015, 2016, 2021, 2023, 2025]. - Part (c) [10M]: Circular Current Loop Axis Field Derivation Bz = μ₀ I b^2 / (2(b^2 + z^2)^(3/2))
[PYQ: 2016, 2018, 2020, 2022].
Question 6: Vector Magnetic Potential & Boundary Conditions (35 Marks) [100% Probability]
- Part (a) [12M]: Vector Magnetic Potential Definition (B = ∇ A) & Vector Poisson’s Equation Derivation (∇^2 A = -μ₀ J)
[PYQ: 2016, 2018, 2019, 2024]. - Part (b) [13M]: Magnetostatic Boundary Conditions (B1n = B2n, H1t - H2t = Js) & Magnetic Refraction Law tanθ1 / tanθ2 = μ1 / μ2
[PYQ: 2016, 2019, 2022, 2025]. - Part (c) [10M]: Hall Effect Principle & Voltage Formula VH = B I / (n q w)
[PYQ: 2018, 2021, 2024].
Question 7: Wave Equations & Conductor Parameters (35 Marks) [100% Probability]
- Part (a) [12M]: 3D Vector Wave Equations for E and H in Source-Free Media (∇^2 E - με ∂^2E/∂t^2 = 0)
[PYQ: 2018, 2019, 2024]. - Part (b) [13M]: Plane Waves in Good Conductors: Attenuation α = √(π f μ σ), Phase β = √(π f μ σ), and Skin Depth δ = 1 / √(π f μ σ)
[PYQ: 2015–2025]. - Part (c) [10M]: Solved PYQ Numerical on Seawater / Conductor Wave Parameters (α, β, η, δ)
[PYQ: 2016, 2020, 2024].
Question 8: Wave Reflection & Radio Propagation (35 Marks) [100% Probability]
- Part (a) [13M]: Normal Incidence Reflection (Γ = (η2 - η1) / (η2 + η1)) & Transmission (τ = 2η2 / (η2 + η1)) Coefficients Proof + 1 + Γ = τ
[PYQ: 2015, 2017, 2022, 2025]. - Part (b) [12M]: Ionospheric Sky-Wave Radio Propagation: Refractive index n = √(1 - 81N/f^2), Critical Frequency fc = 9√Nmax, and MUF = fc secθi
[PYQ: Heavily Tested: 2015–2025]. - Part (c) [10M]: Solved PYQ Numerical on Wave Reflection at Dielectric Boundary or Ionospheric MUF
[PYQ: 2017, 2022, 2025].