Based on detailed analysis of last 5 years' papers. Perfect for 2026 Boards prep!
| Question Example | Type/Marks | Years Repeated | Notes |
|---|---|---|---|
| Explain the need for displacement current. Show how Maxwell modified Ampere’s circuital law. Write Maxwell’s equations in integral form. | Derivation/Theory (3-4 marks) | 2021, 2022, 2023, 2024, 2025 | Repeated 5x; Displacement current Id = ε₀ dΦ_E/dt; Modified Ampere: ∮ B·dl = μ₀ (I_conduction + I_displacement); Maxwell’s 4 equations. |
| Derive expression for speed of electromagnetic waves in vacuum. Show that EM waves are transverse. Mention properties (no medium needed, carry energy/momentum, obey superposition, exert pressure). | Derivation (4 marks) | 2021 Term 2, 2022, 2023, 2024 | Repeated 4x; From Maxwell: c = 1/√(μ₀ε₀) ≈ 3×10⁸ m/s; E & B perpendicular to each other & propagation direction → transverse. |
| Give electromagnetic spectrum with approximate wavelength range, frequency range, production method & uses of each part (radio, microwave, IR, visible, UV, X-ray, gamma rays). | Short Answer/Table (3 marks) | 2022, 2023, 2024, 2025 | Repeated 4x; Memorize table: Radio (km to mm) → antenna, Microwave (mm to cm) → radar/oven, IR (700 nm-1 mm) → heat, Visible (400-700 nm) → vision, UV (10-400 nm) → sterilization, X-ray (0.01-10 nm) → medical imaging, Gamma (<0.01 nm) → nuclear. |
| Assertion: Electromagnetic waves are transverse in nature. Reason: Oscillating electric & magnetic fields are perpendicular to each other and to direction of propagation. | Assertion-Reason (1 mark) | 2023, 2024, 2025 | Repeated 3x; Both true, reason explains. |
| What is Poynting vector? Give its expression & significance (energy flux, direction of energy flow). | Short Answer (2 marks) | 2021 Term 1, 2022, 2023, 2025 | Repeated 4x; S = (1/μ₀) (E × B); magnitude = energy flux (power/area), direction = propagation direction. |
| Explain Hertz experiment to produce & detect electromagnetic waves. | Short Answer (2-3 marks) | 2022, 2024 | Repeated 2x; Spark gap transmitter (LC oscillator) → produces high frequency EM waves → detected by receiving loop with spark. |
| MCQ: The speed of electromagnetic waves in vacuum is: (a) 3×10⁸ m/s (b) depends on frequency (c) depends on medium (d) infinite | MCQ (1 mark) | 2021 Term 1, 2023, 2024 | Repeated 3x; Answer (a) 3×10⁸ m/s (c = 1/√(μ₀ε₀)). |
| Why electromagnetic waves do not require medium for propagation? Compare with mechanical waves. | Short Answer (2 marks) | 2023, 2025 | Repeated 2x; Self-sustaining (changing E produces B & vice versa); Mechanical waves need medium for oscillation. |
| Case-based: Given EM wave properties or spectrum part, identify wave type, uses, or calculate energy/wavelength/frequency. | Case-Based (4 marks) | 2023, 2025 | Repeated 2x; Use c = fλ, energy E = hf for photons (higher frequency → higher energy). |
| Find displacement current density J_d = ε₀ dE/dt or total displacement current in a capacitor. | Short Answer (2 marks) | 2021 Term 2, 2024 | Repeated 2x; Id = ε₀ dΦ_E/dt = C dV/dt (in charging capacitor). |
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