EMFT - ECE
Electric and Magnetic Fields
Practice questions from Electric and Magnetic Fields.
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IncorrectA square metal sheet of is placed on the plane as shown in the figure below.
If the surface charge density (in ) on the sheet is , then the total charge (in , rounded off to the nearest integer) on the sheet is _________.
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Sign in to UnlockAn electric field of is applied along the length of a copper wire of circular cross-section with diameter 1 mm. Copper has a conductivity of .
The current (in Amperes, rounded off to two decimal places) flowing through the wire is _________.
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Sign in to UnlockTwo resistors are connected in a circuit loop of area , as shown in the figure below. The circuit loop is placed on the plane.
When a time-varying magnetic flux, with flux-density (in Tesla), is applied along the positive -axis, the magnitude of current (in Amperes, rounded off to two decimal places) in the loop is _________.
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Sign in to UnlockLet be the unit vectors along x and y axes, respectively and let A be a positive constant. Which one of the following statements is true for the vector fields
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Sign in to UnlockA uniform plane wave with electric field is travelling in the air (relative permittivity, and relative permeability, ) in the direction ( is a positive constant, is the unit vector along the axis). It is incident normally on an ideal electric conductor (conductivity, ) at . The position of the first null of the total magnetic field in the air (measured from , in metres) is
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Sign in to UnlockLet and represent density and velocity, respectively, at a point and time t. Assume is continuous. Let be an arbitrary volume in space enclosed by the closed surface and be the outward unit normal of Which of the following equations is/are equivalent to ?
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Sign in to UnlockIn a circuit, there is a series connection of an ideal resistor and an ideal capacitor. The conduction current (in Amperes) through the resistor is ). The displacement current (in Amperes) through the capacitor is ________.
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Sign in to UnlockIn an electrostatic field, the electric displacement density vector, , is given by
where are the unit vectors along -axis, -axis, and -axis, respectively. Consider a cubical region centered at the origin with each side of length , and vertices at . The electric charge enclosed within is ________ C (rounded off to two decimal places).
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Sign in to UnlockIn the table shown, List-I and List-II respectively, contain terms appearing on the left-hand side and the right-hand side of Maxwell’s equations (in their standard form). Match the left-hand side with corresponding right-hand side
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Sign in to UnlockWhat is the electric flux through a quarter cylinder of height H (as shown in the figure) due to an infinitely long line charge along the axis of the cylinder with a charge density of Q?
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Sign in to UnlockTwo identical copper wires W1 and W2 placed in parallel as shown in the figure, carry current I and 2I respectively, in opposite direction. If the two wires are separated by a distance of 4r, then the magnitude of the magnetic field between the wires at a distance r from W1 is
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Sign in to UnlockTwo conducting spheres S1 and S2 of radii a and b (b > a) respectively, are placed far apart and connected by a long, thin conducting wire, as shown in the figure.
For some charge placed on this structure, the potential and surface electric field on S1 are and , and that on S2 are and , respectively. Then, which of the following is CORRECT?
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Sign in to UnlockIf the vector function
is irrotational, then the values of the constants , respectively, are
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Sign in to UnlockAn electron is moving in free space with velocity towards a stationary electron far away. The closest distance that this moving electron gets to the stationary electron before the repulsive force diverts its path is ____________ .
[Given, mass of electron , charge of electron , and permittivity ]
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Sign in to UnlockConcentric spherical shells of radii 2 m, 4 m, and 8 m carry uniform surface charge densities of , and , respectively. The value of required to ensure that the electric flux density at radius 10 m is______________
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Sign in to UnlockThe current density in a medium is given by
The total current and the average current density flowing through the portion of a spherical surfaceare given, respectively, by
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Sign in to UnlockA uniform and constant magnetic field exists in the direction in vacuum. A particle of mass m with a small charge q is introduced into this region with an initial velocity. Given that B, m, q, and are all non-zero, which one of the following describes the eventual trajectory of the particle?
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Sign in to UnlockThe parallel-plate capacitor shown in the figure has movable plates. The capacitor is charged so that the energy stored in it is 𝐸 when the plate separation is d. The capacitor is then isolated electrically and the plates are moved such that the plate separation becomes 2d.
At this new plate separation, what is the energy stored in the capacitor, neglecting fringing effects?
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Sign in to UnlockA positive charge q is placed at x=0 between two infinite metal plates placed at x=-d and at x=+d respectively. The metal plates lie in the yz plane.
The charge is at rest at t=0, when a voltage +V is applied to the plate at -d and voltage -V is applied to the plate at x=+d. Assume that the quantity of the charge 𝑞 is small enough that it does not perturb the field set up by the metal plates. The time that the charge q takes to reach the right plate is proportional to
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Sign in to UnlockFaraday’s law of electromagnetic induction is mathematically described by which one of the following equations?
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Sign in to UnlockConsider a straight, infinitely long, current carrying conductor lying on the z-axis. Which one of the following plots (in linear scale) qualitatively represents the dependence of Hφ on r, where Hφ is the magnitude of the azimuthal component of magnetic field outside the conductor and r is the radial distance from the conductor?
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Sign in to UnlockIn a source free region in vacuum, if the electrostatic potential, the value of constant c must be _______.
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Sign in to UnlockThe electric field of a plane wave propagating in a lossless non-magnetic medium is given by the following expression
The type of the polarization is
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Sign in to UnlockA coaxial capacitor of inner radius 1 mm and outer radius 5 mm has a capacitance per unit length of 172pF/m. If the ratio of outer radius to inner radius is doubled, the capacitance per unit length (in pF/m) is ________.
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Sign in to UnlockThe force on a point charge +q kept at a distance d from the surface of an infinite grounded metal plate in a medium of permittivity ∈ is
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Sign in to UnlockGiven the vector
,
where denote unit vectors along xy directions, respectively. The magnitude of curl of A is ________.
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Sign in to UnlockA region shown below contains a perfect conducting half-space and air. The surface current on the surface of the perfect conductor is amperes per meter. The tangential field in the air just above the perfect conductor is
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Sign in to UnlockThe electric field (assumed to be one-dimensional) between two points A and B is shown. Let and be the electrostatic potentials at A and B, respectively. The value of in Volts is ________.
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Sign in to UnlockGiven . If S represents the portion of the sphere for z ≥ 0 , then is______________.
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Sign in to UnlockIf is the electric field in a source free region, a valid expression for the electrostatic potential is
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Sign in to UnlockThe divergence of the vector field is
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Sign in to UnlockAn infinitely long uniform solid wire of radius a carries a uniform dc current of density j.
The magnetic field at a distance r from the center of the wire is proportional to
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Sign in to UnlockAn infinitely long uniform solid wire of radius a carries a uniform dc current of density j.
A hole of radius b (b < a) is now drilled along the length of the wire at a distance d from the center of the wire as shown below.
The magnetic field inside the hole is
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Sign in to UnlockA current sheet A/m lies on the dielectric interface x=0 between two dielectric media with, in Region-1 and , in Region-2 . If the magnetic field in Region-1 at is A/m, the magnetic field in Region-2 at is
(Region-2): ,
(Region-1): ,
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Sign in to UnlockTwo infinitely long wires carrying current are as shown in the figure below. One wire is in the y-z plane and parallel to the y-axis. The other wire is in the x-y plane and parallel to the x-axis. Which components of the resulting magnetic field are non-zero at the origin?
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Sign in to UnlockA magnetic field in air is measured to be
What current distribution leads to this field?
[Hint: The algebra is trivial in cylindrical coordinates.]
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Sign in to UnlockFor static electric and magnetic fields in an inhomogeneous source-free-medium, which of the following represents the correct form of two of Maxwell’s equations?
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Sign in to UnlockIf C is a closed curve enclosing a surface S, then the magnetic field intensity, the current density and the electric flux density are related by
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Sign in to UnlockA medium is divided into regions I and II about x = 0 plane, as shown in the figure below. An electromagnetic wave with electric field is incident normally on the interface form region-I. The electric field in region-II at the interface is:
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Sign in to UnlockA parallel plate air-filled capacitor has plate area of and plate separation of . It is connected to a 0.5 V, 3.6 GHz source. The magnitude of the displacement current is
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Sign in to UnlockThe unity of is
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Sign in to UnlockMedium 1 has the electrical permittivity farad/m and occupies the region to the left of plane. Medium 2 has the electrical permittivity farad/m and occupies the region to the right of plane. If in medium 1 is volt/m, then in medium 2 is
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Sign in to UnlockIf the electric field intensity is given by volt/m, the potential difference between X (2,0, 0) and Y (1, 2, 3) is
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Sign in to UnlockIf the electric field intensity associated with a uniform plane electromagnetic wave travelling in a perfect dielectric medium is give by
volt/m, then the velocity of the travelling wave is
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Sign in to UnlockDistilled water at 25º C is characterized by mho/m and at a frequency of 3 GHz. Its loss tangent tan δ is
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Sign in to UnlockThe electric field on the surface of a perfect conductor is 2 V/m. The conductor is immersed in water with . The surface charge density on the conductor is
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Sign in to UnlockGiven in free space.
(a) Write all the four Maxwell’s equations in free space.
(b) Find . (c) Find H
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Sign in to UnlockAn electric field on a plane is described by its potential where r is the distance from the source. The field is due to
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Sign in to UnlockThe Maxwell equation is based on
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Sign in to UnlockA loop is rotating about the y-axis in a magnetic field . The voltage in the loop is
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Sign in to UnlockGiven an irrotational vector field
Find . at (1, 1, -2)
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Sign in to UnlockA metal sphere with 1 m radius and a surface charge density of is enclosed in a cube of 10 m side. The total outward electric displacement normal to the surface of the cube is
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Sign in to UnlockMatch the following
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Sign in to UnlockThe electric field strength at a distance point, P, due to a point charge, +q. located on the origin, is . If the point charge is now enclosed by a perfectly conducting metal sheet sphere whose centre is at the origin, then the electric field strength at the point. P. outside the sphere becomes.
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Sign in to UnlockIn the infinite plane, , there exists a uniform surface charge density of . The associated electric field strength is
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Sign in to UnlockMatch list I and list II and select answer using the code given below:-
(a)
(b)
(c)
(1) Continuity equation
(2) Faraday’s law
(3) Ampere’s law
(4) Gauss’s law
(5) Biot-Savart law
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Sign in to UnlockFor a uniformly charged sphere of radius R and charge density p, the ratio of magnitude of electric fields at distance and 2R from the centre, i.e.,
is ___________
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Sign in to UnlockA long solenoid of radius R, and having N turns per unit length carries a time dependent current. The magnitude of induced electric field at a distance radially from the axis of the solenoid is
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Sign in to UnlockMatch the following descriptions with each of the diagrams given in figure. Fields are near the interface, but on opposite sides of the boundary. Vectors are drawn to scale.
(a) Medium 1 and medium 2 are dielectrics with
(b) Medium 1 and medium 2 are dielectrics with
(c) Medium 2 is a perfect conductor
(d) Medium 1 is a perfect conductor.
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