60 solved GATE EC questions on Electromagnetics, drawn from 11 exam years and grouped by year. Every question shows the official answer and a step-by-step solution.
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Use the field symmetry to select Gauss's law, Ampère's law, or a direct integral, then verify boundary conditions. These selected foundations connect electrostatics, magnetostatics, and wave propagation. The original exercises use ideal geometries and lossless media.
Our study notes and original examples support the PYQs below; they are not official exam questions or a replacement for the current syllabus.
The divergence of D equals the volume charge density: ∇·D = ρv. For highly symmetric charge distributions, Gauss's law in integral form directly gives D. The electric field E = D/ε in linear isotropic media. Potential difference is the negative line integral of E.
Check yourself: Does the chosen Gaussian surface exploit the charge symmetry?
The curl of H equals the volume current density: ∇×H = J (static case). For symmetric current distributions, Ampère's circuital law gives H directly. B = μH in linear isotropic media. The Biot-Savart law handles arbitrary current geometries but requires integration.
Check yourself: Is the Amperian path chosen so that H is constant and tangent along it?
At a boundary between two media: tangential E is continuous; normal D jumps by surface charge density. Tangential H jumps by surface current density; normal B is continuous. These conditions determine the refraction of fields at interfaces.
Check yourself: Have you identified whether surface charges or currents exist at the boundary?
In a lossless medium, a uniform plane wave propagates at v = 1/√(με) with intrinsic impedance η = √(μ/ε). E and H are perpendicular to each other and to the propagation direction. The time-average Poynting vector gives power flow per unit area: S = |E|²/(2η).
Check yourself: Are E, H, and the propagation direction mutually orthogonal?
A lossless transmission line has characteristic impedance Z₀ = √(L/C) per unit length. The reflection coefficient at a load is Γ = (ZL − Z₀)/(ZL + Z₀). The voltage standing wave ratio is VSWR = (1 + |Γ|)/(1 − |Γ|). A matched load (ZL = Z₀) eliminates reflections.
Check yourself: Is the impedance measured at the load or at a different point along the line?
Original teaching example · not a PYQ
Original mini-example: an infinite line charge of density ρL = 10 nC/m is located along the z-axis in free space (ε₀ = 8.854 × 10⁻¹² F/m). Find E at a radial distance ρ = 2 m from the line.
E ≈ 89.9 V/m radially outward at ρ = 2 m.
A lossless transmission line has Z₀ = 50 Ω and is terminated with a load ZL = 150 Ω. Find the reflection coefficient and VSWR.
Γ = 0.5; VSWR = 3.
Γ = (150 − 50)/(150 + 50) = 100/200 = 0.5. VSWR = (1 + 0.5)/(1 − 0.5) = 1.5/0.5 = 3. A real positive Γ indicates the reflected wave is in phase with the incident wave at the load.
Supplemental reading, not an official GATE reading list or an endorsement of these notes.
Free supplemental lectures, problem sets, and solutions covering electrostatics, magnetostatics, waves, transmission lines, and antennas.
This page shows 60 recent questions from the released archive, newest first. For older questions and complete papers, browse all GATE EC papers. Questions can carry more than one subject tag; counts are not marks weightage.
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