GATE EE Electromagnetic Fields Previous Year Questions

56 solved GATE EE questions on Electromagnetic Fields, drawn from 13 exam years and grouped by year. Every question shows the official answer and a step-by-step solution.

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Electromagnetic Fields: choose the symmetry, then apply the law

Identify the charge or current distribution's symmetry before selecting a Gaussian surface or Amperian loop. These selected foundations connect electrostatics, magnetostatics, Maxwell's equations, and wave propagation through original exercises. State boundary conditions and medium properties explicitly.

Our study notes and original examples support the PYQs below; they are not official exam questions or a replacement for the current syllabus.

Before you start

  • Vector calculus: gradient, divergence, curl, and the divergence and Stokes theorems.
  • Coordinate systems (Cartesian, cylindrical, spherical) and unit-vector conventions.

Concepts to revise before solving

Coulomb's law and electrostatic potential

The electric field from a point charge Q in free space is E = Q/(4πε₀r²) directed radially. Potential is V = Q/(4πε₀r), defined relative to a zero reference. E = −∇V relates field to potential. Superposition applies for multiple charges.

Check yourself: Is your reference potential at infinity, and does the field point from high to low potential?

Gauss's law and divergence

Gauss's law in integral form states ∮ D·dS = Q_enc. In differential form, ∇·D = ρ_v. Choose a Gaussian surface that exploits symmetry so D is constant on the surface and either parallel or perpendicular to dS. Without symmetry, use superposition or the differential form.

Check yourself: Is D constant in magnitude and aligned with the surface normal everywhere on your Gaussian surface?

Biot–Savart law and Ampère's law

The Biot–Savart law gives the magnetic field from a current element: dB = μ₀ I dl × r̂ / (4πr²). Ampère's law ∮ H·dl = I_enc simplifies calculations when current symmetry allows H to be factored out of the integral. The right-hand rule determines field direction.

Check yourself: Does your Ampèrian loop lie on a surface where H is constant and tangential?

Maxwell's equations and boundary conditions

Maxwell's four equations unify electrostatics, magnetostatics, and time-varying fields. At a boundary between two media, the tangential component of E and the normal component of B are continuous (in the absence of surface charge and current). Boundary conditions determine reflection and transmission of waves.

Check yourself: Have you matched both tangential and normal components at the interface?

Uniform plane wave propagation

In a lossless medium, a uniform plane wave has E and H perpendicular to each other and to the propagation direction. The intrinsic impedance is η = √(μ/ε), and the phase velocity is v_p = 1/√(με). In free space, η₀ = 120π ≈ 377 Ω and v_p = c.

Check yourself: Are E, H, and the propagation direction mutually orthogonal and right-handed?

Mistakes to avoid

Applying Gauss's law with a surface that lacks the required symmetry.
The law is always true, but it simplifies the calculation only when symmetry makes D constant on the surface. Otherwise use superposition or the differential form.
Forgetting that the divergence of B is always zero.
∇·B = 0 states that magnetic monopoles do not exist. Any field solution must satisfy this; a nonzero divergence signals an error.
Using the free-space intrinsic impedance for a wave in a dielectric medium.
In a medium with relative permittivity ε_r and relative permeability μ_r, use η = η₀√(μ_r/ε_r).

Original teaching example · not a PYQ

Work through the reasoning

Original mini-example: a solid sphere of radius R carries a uniform volume charge density ρ C/m³ in free space. Using Gauss's law, find the electric field magnitude at distance r from the centre for r < R and r > R.

  1. By spherical symmetry, E is radial and depends only on r. Choose a concentric Gaussian sphere of radius r.
  2. For r < R: enclosed charge Q_enc = ρ(4πr³/3). Gauss's law gives E(4πr²) = ρ(4πr³/3)/ε₀, so E = ρr/(3ε₀), directed radially outward.
  3. For r > R: enclosed charge is the total Q = ρ(4πR³/3). Gauss's law gives E(4πr²) = ρ(4πR³/3)/ε₀, so E = ρR³/(3ε₀r²).
  4. At r = R, both expressions give E = ρR/(3ε₀), confirming continuity of the electric field at the surface where there is no surface charge.

E = ρr/(3ε₀) for r < R; E = ρR³/(3ε₀r²) for r > R; both directed radially outward.

Try it before reading the answer

The electric field in a region of free space is E = 5r r̂ V/m in spherical coordinates, where r is the radial distance in metres. Find the volume charge density using Gauss's law in differential form.

Show answer and reasoning

ρ_v = 15ε₀ C/m³, approximately 132.8 pC/m³.

In spherical coordinates with a purely radial field, ∇·E = (1/r²) d(r² × 5r)/dr = (1/r²) d(5r³)/dr = 15r²/r² = 15 V/m². From ∇·D = ρ_v and D = ε₀E: ρ_v = 15ε₀ ≈ 15 × 8.854 × 10⁻¹² C/m³.

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Apply this to the previous-year questions

Previous-year questions by year

This page shows 56 recent questions from the released archive, newest first. For older questions and complete papers, browse all GATE EE papers. Questions can carry more than one subject tag; counts are not marks weightage.

GATE EE 20264 questions

  1. Set 1 Q15A uniform ring charge of radius RR carries a total charge QQ. Which one of the following options correctly quantifies the magnitude of the force on a point…MCQ · +1 marks · Easy
  2. Set 1 Q16A positive point charge with velocity v=5x^\vec{v} = 5 \hat{x} enters a region having electric field E=4y^\vec{E} = 4 \hat{y} and magnetic field…MCQ · +1 marks · Easy
  3. Set 1 Q51The figure shows an arbitrarily shaped planar conducting loop A in the XY plane. Two nonintersecting regions with areas a1a_1 and a2a_2 within the loop are…MCQ · +2 marks · Hard
  4. Set 1 Q63A uniform spherical volume charge distribution of radius 22 m, centered at the origin, has a strength of 3π×106\frac{3}{\pi} \times 10^{-6} C/m3^3. A point…NAT · +2 marks · Hard

GATE EE 20253 questions

  1. Set 1 Q25Which one of the following figures represents the radial electric field distribution ERE_R caused by a spherical cloud of electrons with a volume charge…MCQ · +1 marks · Medium
  2. Set 1 Q50An air filled cylindrical capacitor (capacitance C0C_0) of length LL, with aa and bb as its inner and outer radii, respectively, consists of two coaxial…MCQ · +2 marks · Medium
  3. Set 1 Q52Consider two coupled circuits, having self-inductances L1L_1 and L2L_2, that carry non-zero currents I1I_1 and I2I_2, respectively. The mutual inductance…MSQ · +2 marks · Hard

GATE EE 20242 questions

  1. Set 1 Q51In the (x,y,z)(x, y, z) coordinate system, three point-charges QQ, QQ, and αQ\alpha Q are located in free space at (1,0,0)(-1, 0, 0), (1,0,0)(1, 0, 0), and (0,1,0)(0, -1, 0),…NAT · +2 marks · Medium
  2. Set 1 Q52The given equation represents a magnetic field strength H(r,θ,ϕ)\vec{H}(r, \theta, \phi) in the spherical coordinate system, in free space. Here, r^\hat{r} and…NAT · +2 marks · Hard

GATE EE 20233 questions

  1. Set 1 Q43In the figure, the electric field E and the magnetic field B point to x and z directions, respectively, and have constant magnitudes. A positive charge…MSQ · +2 marks · Hard
  2. Set 1 Q53When the winding c-d of the single-phase, 50 Hz, two winding transformer is supplied from an AC current source of frequency 50 Hz, the rated voltage of 200 V…NAT · +2 marks · Hard
  3. Set 1 Q61An infinite surface of linear current density K=5a^x\mathbf{K} = 5\hat{\mathbf{a}}_x A/m exists on the x-y plane, as shown in the figure. The magnitude of the…NAT · +2 marks · Medium

GATE EE 20223 questions

  1. Set 1 Q23A long conducting cylinder having a radius 'b' is placed along the zz axis. The current density is J=Jar3z^J = J_a r^3 \hat{z} for the region r<br < b where rr is…MCQ · +1 marks · Medium
  2. Set 1 Q45If the magnetic field intensity (H\mathbf{H}) in a conducting region is given by the expression,…MCQ · +2 marks · Medium
  3. Set 1 Q53As shown in the figure below, two concentric conducting spherical shells, centered at r=0r = 0 and having radii r=cr = c and r=dr = d are maintained at potentials…MCQ · +2 marks · Medium

GATE EE 20214 questions

  1. Set 1 Q15Which one of the following vector functions represents a magnetic field B\vec{B}? (x^\hat{x}, y^\hat{y}, and z^\hat{z} are unit vectors along x-axis, y-axis,…MCQ · +1 marks · Easy
  2. Set 1 Q27A 1μC1\mu C point charge is held at the origin of a cartesian coordinate system. If a second point charge of 10μC10\mu C is moved from (0,10,0)(0, 10, 0) to (5,5,5)(5, 5, 5)NAT · +1 marks · Medium
  3. Set 1 Q51One coulomb of point charge moving with a uniform velocity 10x^10 \hat{x} m/s enters the region x0x \geq 0 having a magnetic flux density…NAT · +2 marks · Medium
  4. Set 1 Q52Consider a large parallel plate capacitor. The gap dd between the two plates is filled entirely with a dielectric slab of relative permittivity 5. The plates…NAT · +2 marks · Easy

GATE EE 20205 questions

  1. Set 1 Q35The cross-section of a metal-oxide-semiconductor structure is shown schematically. Starting from an uncharged condition, a bias of +3 V+3\text{ V} is applied to…NAT · +1 marks · Hard
  2. Set 1 Q43The static electric field inside a dielectric medium with relative permittivity, εr=2.25\varepsilon_r = 2.25, expressed in cylindrical coordinate system is given by…MCQ · +2 marks · Medium
  3. Set 1 Q50Let ar,aϕ\mathbf{a}_r, \mathbf{a}_\phi and az\mathbf{a}_z be unit vectors along r,ϕr, \phi and zz directions, respectively in the cylindrical coordinate system.…MCQ · +2 marks · Medium
  4. Set 1 Q58Windings 'A', 'B' and 'C' have 20 turns each and are wound on the same iron core as shown, along with winding 'X' which has 2 turns. The figure shows the sense…NAT · +2 marks · Hard
  5. Set 1 Q65A conducting square loop of side length 1 m1\text{ m} is placed at a distance of 1 m1\text{ m} from a long straight wire carrying a current I=2 AI = 2\text{ A} as…NAT · +2 marks · Medium

GATE EE 20192 questions

  1. Set 1 Q30A co-axial cylindrical capacitor shown in Figure (i) has dielectric with relative permittivity ϵr1=2\epsilon_{r1} = 2. When one-fourth portion of the dielectric…NAT · +1 marks · Medium
  2. Set 1 Q54The magnetic circuit shown below has uniform cross-sectional area and air gap of 0.2 cm0.2 \text{ cm}. The mean path length of the core is 40 cm40 \text{ cm}. Assume…NAT · +2 marks · Medium

GATE EE 20183 questions

  1. Set 1 Q20A positive charge of 11 nC is placed at (0,0,0.2)(0, 0, 0.2) where all dimensions are in metres. Consider the xyx - y plane to be a conducting ground plane. Take…MCQ · +1 marks · Medium
  2. Set 1 Q36A transformer with toroidal core of permeability μ\mu is shown in the figure. Assuming uniform flux density across the circular core cross-section of radius…MCQ · +2 marks · Medium
  3. Set 1 Q55The capacitance of an air-filled parallel-plate capacitor is 6060 pF. When a dielectric slab whose thickness is half the distance between the plates, is placed…NAT · +2 marks · Medium

GATE EE 20175 questions

  1. Set 1 Q4A solid iron cylinder is placed in a region containing a uniform magnetic field such that the cylinder axis is parallel to the magnetic field direction. The…MCQ · +1 marks · Medium
  2. Set 1 Q5Consider an electron, a neutron and a proton initially at rest and placed along a straight line such that the neutron is exactly at the center of the line…MCQ · +1 marks · Medium
  3. Set 1 Q44The magnitude of magnetic flux density (B) in micro Teslas (μT\mu T), at the center of a loop of wire wound as a regular hexagon of side length 1 m carrying a…NAT · +2 marks · Medium
  4. Set 2 Q2Consider a solid sphere of radius 5 cm made of a perfect electric conductor. If one million electrons are added to this sphere, these electrons will be…MCQ · +1 marks · Easy
  5. Set 2 Q55A thin soap bubble of radius R=1 cmR = 1\text{ cm}, and thickness a=3.3 μma = 3.3\text{ }\mu\text{m} (aRa \ll R), is at a potential of 1 V1\text{ V} with respect to a…NAT · +2 marks · Hard

GATE EE 20166 questions

  1. Set 1 Q23In cylindrical coordinate system, the potential produced by a uniform ring charge is given by ϕ=f(r,z)\phi = f(r, z), where ff is a continuous function of rr and…MCQ · +1 marks · Medium
  2. Set 1 Q24A soft-iron toroid is concentric with a long straight conductor carrying a direct current II. If the relative permeability μr\mu_r of soft-iron is 100, the…NAT · +1 marks · Medium
  3. Set 1 Q48Two electric charges qq and 2q-2q are placed at (0,0)(0,0) and (6,0)(6,0) on the x-y plane. The equation of the zero equipotential curve in the x-y plane isMCQ · +2 marks · Medium
  4. Set 2 Q26A parallel plate capacitor filled with two dielectrics is shown in the figure below. If the electric field in the region A is 4 kV/cm4\text{ kV/cm}, the electric…MCQ · +1 marks · Easy
  5. Set 2 Q35Two electrodes, whose cross-sectional view is shown in the figure below, are at the same potential. The maximum electric field will be at the point [figure]MCQ · +1 marks · Easy
  6. Set 2 Q65A rotating conductor of 1 m1\text{ m} length is placed in a radially outward (about the zz-axis) magnetic flux density (BB) of 1 Tesla1\text{ Tesla} as shown in…NAT · +2 marks · Medium

GATE EE 20158 questions

  1. Set 1 Q21Consider a one-turn rectangular loop of wire placed in a uniform magnetic field as shown in the figure. The plane of the loop is perpendicular to the field…NAT · +1 marks · Medium
  2. Set 1 Q32The self inductance of the primary winding of a single phase, 50Hz50 Hz, transformer is 800mH800 mH, and that of the secondary winding is 600mH600 mH. The mutual…MCQ · +1 marks · Medium
  3. Set 1 Q46A parallel plate capacitor is partially filled with glass of dielectric constant 4.04.0 as shown below. The dielectric strengths of air and glass are…NAT · +2 marks · Medium
  4. Set 2 Q13Match the following. | P. Stokes's Theorem | 1. Dds=Q\oiint \mathbf{D} \cdot d\mathbf{s} = Q | | ------ | ------ | | Q. Gauss's Theorem | 2. f(z)dz=0\oint f(z) dz = 0 |…MCQ · +1 marks · Easy
  5. Set 2 Q19Two semi-infinite dielectric regions are separated by a plane boundary at y=0y = 0. The dielectric constants of region 1 (y<0y < 0) and region 2 (y>0y > 0) are 2…MCQ · +1 marks · Easy
  6. Set 2 Q20A circular turn of radius 1 m revolves at 60 rpm about its diameter aligned with the x-axis as shown in the figure. The value of μ0\mu_0 is…NAT · +1 marks · Medium
  7. Set 2 Q46Two semi-infinite conducting sheets are placed at right angles to each other as shown in the figure. A point charge of +Q+Q is placed at a distance of dd from…MCQ · +2 marks · Hard
  8. Set 2 Q56Two identical coils each having inductance LL are placed together on the same core. If an overall inductance of αL\alpha L is obtained by interconnecting…NAT · +2 marks · Medium

GATE EE 20148 questions

  1. Set 1 Q17C0C_0 is the capacitance of a parallel plate capacitor with air as dielectric (as in figure (a)). If, half of the entire gap as shown in figure (b) is filled…MCQ · +1 marks · Easy
  2. Set 1 Q22For a specified input voltage and frequency, if the equivalent radius of the core of a transformer is reduced by half, the factor by which the number of turns…MCQ · +1 marks · Medium
  3. Set 1 Q24The undesirable property of an electrical insulating material isMCQ · +1 marks · Easy
  4. Set 1 Q42The following four vector fields are given in Cartesian co-ordinate system. The vector field which does not satisfy the property of magnetic flux density isMCQ · +2 marks · Easy
  5. Set 2 Q18A parallel plate capacitor consisting two dielectric materials is shown in the figure. The middle dielectric slab is placed symmetrically with respect to the…MCQ · +1 marks · Medium
  6. Set 2 Q42The magnitude of magnetic flux density (B\vec{B}) at a point having normal distance dd meters from an infinitely extended wire carrying current of II A is…MCQ · +2 marks · Medium
  7. Set 3 Q17A hollow metallic sphere of radius rr is kept at potential of 1 Volt. The total electric flux coming out of the concentric spherical surface of radius RRMCQ · +1 marks · Medium
  8. Set 3 Q41A perfectly conducting metal plate is placed in xx-yy plane in a right handed coordinate system. A charge of +32πϵo2+32\pi\epsilon_o\sqrt{2} columbs is placed at…MCQ · +2 marks · Medium

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