27 real Electromagnetic Fields questions from the Electrical Core bank, as asked in Indian campus drives and tech interviews. Every question has a verified answer and an AI-tutor explanation on placd — free to start.
1. What is Gauss's law?
Junior
A.the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible
B.the total electric flux through any closed surface equals the enclosed charge divided by the permittivity of free space
C.the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current
D.tangential E and normal D are continuous across a charge-free interface, while normal E jumps by the ratio of the two permittivities
A.Gauss's law — the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible
B.Gauss's law — tangential E and normal D are continuous across a charge-free interface, while normal E jumps by the ratio of the two permittivities
C.Gauss's law — depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability
D.Gauss's law — the total electric flux through any closed surface equals the enclosed charge divided by the permittivity of free space
A.Faraday's law of induction — the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible
B.Faraday's law of induction — Laplacian of electric potential equals minus the charge density divided by permittivity, reducing to Laplace's equation in charge-free regions
C.Faraday's law of induction — the total electric flux through any closed surface equals the enclosed charge divided by the permittivity of free space
D.Faraday's law of induction — the emf induced in a closed loop equals the negative rate of change of magnetic flux linking that loop
8. Which term means: "the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current"?
A.Ampere's circuital law — Laplacian of electric potential equals minus the charge density divided by permittivity, reducing to Laplace's equation in charge-free regions
B.Ampere's circuital law — the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current
C.Ampere's circuital law — tangential E and normal D are continuous across a charge-free interface, while normal E jumps by the ratio of the two permittivities
D.Ampere's circuital law — the emf induced in a closed loop equals the negative rate of change of magnetic flux linking that loop
A.tangential E and normal D are continuous across a charge-free interface, while normal E jumps by the ratio of the two permittivities
B.the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible
C.magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product
D.depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability
11. Which term means: "magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product"?
A.Biot-Savart law — the emf induced in a closed loop equals the negative rate of change of magnetic flux linking that loop
B.Biot-Savart law — the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current
C.Biot-Savart law — magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product
D.Biot-Savart law — depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability
A.the induced current flows in a direction that opposes the change in flux producing it, expressing conservation of energy
B.the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current
C.magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product
D.the total electric flux through any closed surface equals the enclosed charge divided by the permittivity of free space
A.Lenz's law — the total electric flux through any closed surface equals the enclosed charge divided by the permittivity of free space
B.Lenz's law — the induced current flows in a direction that opposes the change in flux producing it, expressing conservation of energy
C.Lenz's law — the emf induced in a closed loop equals the negative rate of change of magnetic flux linking that loop
D.Lenz's law — magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product
17. Which term means: "Laplacian of electric potential equals minus the charge density divided by permittivity, reducing to Laplace's equation in charge-free regions"?
A.Poisson's equation — magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product
B.Poisson's equation — Laplacian of electric potential equals minus the charge density divided by permittivity, reducing to Laplace's equation in charge-free regions
C.Poisson's equation — the emf induced in a closed loop equals the negative rate of change of magnetic flux linking that loop
D.Poisson's equation — depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability
A.the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current
B.the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible
C.depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability
D.magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product
20. Which term means: "depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability"?
A.Skin depth — depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability
B.Skin depth — the emf induced in a closed loop equals the negative rate of change of magnetic flux linking that loop
C.Skin depth — the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current
D.Skin depth — the induced current flows in a direction that opposes the change in flux producing it, expressing conservation of energy
23. Which term means: "tangential E and normal D are continuous across a charge-free interface, while normal E jumps by the ratio of the two permittivities"?
A.Dielectric boundary conditions — depth at which current density in a conductor falls to 1/e of its surface value, decreasing with frequency, conductivity and permeability
B.Dielectric boundary conditions — tangential E and normal D are continuous across a charge-free interface, while normal E jumps by the ratio of the two permittivities
C.Dielectric boundary conditions — Laplacian of electric potential equals minus the charge density divided by permittivity, reducing to Laplace's equation in charge-free regions
D.Dielectric boundary conditions — the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible
26. Which term means: "the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible"?
A.Displacement current — magnetic field from a current element is proportional to the current and inversely proportional to the square of the distance, directed by the cross product
B.Displacement current — the induced current flows in a direction that opposes the change in flux producing it, expressing conservation of energy
C.Displacement current — the line integral of magnetic field intensity around a closed path equals the conduction current enclosed plus displacement current
D.Displacement current — the dD/dt term Maxwell added so that a changing electric field produces a magnetic field, which makes wave propagation possible
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