600+ Electromagnetics Solved MCQs

1.

Gradient of a function is a constant. State True/False.

A. true
B. false
Answer» B. false
2.

The mathematical perception of the gradient is said to be

A. tangent
B. chord
C. slope
D. arc
Answer» C. slope
3.

Divergence of gradient of a vector function is equivalent to

A. laplacian operation
B. curl operation
C. double gradient operation
D. null vector
Answer» A. laplacian operation
4.

Curl of gradient of a vector is

A. unity
B. zero
C. null vector
D. depends on the constants of the vector
Answer» C. null vector
5.

Find the gradient of the function given by, x2 + y2 + z2 at (1,1,1)

A. i + j + k
B. 2i + 2j + 2k
C. 2xi + 2yj + 2zk
D. 4xi + 2yj + 4zk
Answer» B. 2i + 2j + 2k
6.

The gradient can be replaced by which of the following?

A. maxwell equation
B. volume integral
C. differential equation
D. surface integral
Answer» C. differential equation
7.

. Find the gradient of the function sin x + cos y.

A. cos x i – sin y j
B. cos x i + sin y j
C. sin x i – cos y j
D. sin x i + cos y j
Answer» A. cos x i – sin y j
8.

The divergence of a vector is a scalar. State True/False.

A. true
B. false
Answer» A. true
9.

The divergence concept can be illustrated using Pascal’s law. State True/False.

A. true
B. false
Answer» A. true
10.

Compute the divergence of the vector xi + yj + zk.

A. 0
B. 1
C. 2
D. 3
Answer» D. 3
11.

Find the divergence of the vector yi + zj + xk.

A. -1
B. 0
C. 1
D. 3
Answer» B. 0
12.

Find the divergence of the vector F= xe-x i + y j – xz k

A. (1 – x)(1 + e-x)
B. (x – 1)(1 + e-x)
C. (1 – x)(1 – e)
D. (x – 1)(1 – e)
Answer» A. (1 – x)(1 + e-x)
13.

Find whether the vector is solenoidal, E = yz i + xz j + xy k

A. yes, solenoidal
B. no, non-solenoidal
C. solenoidal with negative divergence
D. variable divergence
Answer» A. yes, solenoidal
14.

Find the divergence of the field, P = x2yz i + xz k

A. xyz + 2x
B. 2xyz + x
C. xyz + 2z
D. 2xyz + z
Answer» B. 2xyz + x
15.

Identify the nature of the field, if the divergence is zero and curl is also zero.

A. solenoidal, irrotational
B. divergent, rotational
C. solenoidal, irrotational
D. divergent, rotational
Answer» C. solenoidal, irrotational
16.

Curl is defined as the angular velocity at every point of the vector field. State True/False.

A. true
B. false
Answer» A. true
17.

The curl of curl of a vector is given by,

A. div(grad v) – (del)2v
B. grad(div v) – (del)2v
C. (del)2v – div(grad v)
D. (del)2v – grad(div v)
Answer» B. grad(div v) – (del)2v
18.

Which of the following theorem use the curl operation?

A. green’s theorem
B. gauss divergence theorem
C. stoke’s theorem
D. maxwell equation
Answer» C. stoke’s theorem
19.

The curl of a curl of a vector gives a

A. scalar
B. vector
C. zero value
D. non zero value
Answer» B. vector
20.

Is the vector is irrotational. E = yz i + xz j + xy k

A. yes
B. no
Answer» A. yes
21.

Find the curl of A = (y cos ax)i + (y + ex)k

A. 2i – ex j – cos ax k
B. i – ex j – cos ax k
C. 2i – ex j + cos ax k
D. i – ex j + cos ax k
Answer» B. i – ex j – cos ax k
22.

Find the curl of the vector A = yz i + 4xy j + y k

A. xi + j + (4y – z)k
B. xi + yj + (z – 4y)k
C. i + j + (4y – z)k
D. i + yj + (4y – z)k
Answer» D. i + yj + (4y – z)k
23.

Curl cannot be employed in which one of the following?

A. directional coupler
B. magic tee
C. isolator and terminator
D. waveguides
Answer» D. waveguides
24.

Which of the following Maxwell equations use curl operation?

A. maxwell 1st and 2nd equation
B. maxwell 3rd and 4th equation
C. all the four equations
D. none of the equations
Answer» A. maxwell 1st and 2nd equation
25.

The integral form of potential and field relation is given by line integral. State True/False

A. true
B. false
Answer» A. true
26.

If V = 2x2y – 5z, find its electric field at point (-4,3,6)

A. 47.905
B. 57.905
C. 67.905
D. 77.905
Answer» B. 57.905
27.

Find the potential between a(-7,2,1) and b(4,1,2). Given E = (-6y/x2 )i + ( 6/x) j + 5 k.

A. -8.014
B. -8.114
C. -8.214
D. -8.314
Answer» C. -8.214
28.

A field in which a test charge around any closed surface in static path is zero is called

A. solenoidal
B. rotational
C. irrotational
D. conservative
Answer» D. conservative
29.

The potential in a lamellar field is

A. 1
B. 0
C. -1
D.
Answer» B. 0
30.

Line integral is used to calculate

A. force
B. area
C. volume
D. length
Answer» D. length
31.

The energy stored in the inductor 100mH with a current of 2A is

A. 0.2
B. 0.4
C. 0.6
D. 0.8
Answer» A. 0.2
32.

Gauss law for electric field uses surface integral. State True/False

A. true
B. false
Answer» A. true
33.

Surface integral is used to compute

A. surface
B. area
C. volume
D. density
Answer» B. area
34.

Coulomb’s law can be derived from Gauss law. State True/ False

A. true
B. false
Answer» A. true
35.

Evaluate Gauss law for D = 5r2/4 i in spherical coordinates with r = 4m and θ = π/2.

A. 600
B. 599.8
C. 588.9
D. 577.8
Answer» C. 588.9
36.

The ultimate result of the divergence theorem evaluates which one of the following?

A. field intensity
B. field density
C. potential
D. charge and flux
Answer» D. charge and flux
37.

The divergence theorem converts

A. line to surface integral
B. surface to volume integral
C. volume to line integral
D. surface to line integral
Answer» B. surface to volume integral
38.

The triple integral is used to compute volume. State True/False

A. true
B. false
Answer» A. true
39.

The volume integral is three dimensional. State True/False

A. true
B. false
Answer» A. true
40.

Using volume integral, which quantity can be calculated?

A. area of cube
B. area of cuboid
C. volume of cube
D. distance of vector
Answer» C. volume of cube
41.

Gauss theorem uses which of the following operations?

A. gradient
B. curl
C. divergence
D. laplacian
Answer» C. divergence
42.

The Gauss divergence theorem converts

A. line to surface integral
B. line to volume integral
C. surface to line integral
D. surface to volume integral
Answer» D. surface to volume integral
43.

Find the divergence theorem value for the function given by (ez, sin x, y2)

A. 1
B. 0
C. -1
D. 2
Answer» B. 0
44.

Divergence theorem computes to zero for a solenoidal function. State True/False.

A. true
B. false
Answer» A. true
45.

Coulomb is the unit of which quantity?

A. field strength
B. charge
C. permittivity
D. force
Answer» B. charge
46.

Coulomb law is employed in

A. electrostatics
B. magnetostatics
C. electromagnetics
D. maxwell theory
Answer» A. electrostatics
47.

Find the force between 2C and -1C separated by a distance 1m in air(in newton).

A. 18 x 106
B. -18 x 106
C. 18 x 10-6
D. -18 x 10-6
Answer» B. -18 x 106
48.

Two charges 1C and -4C exists in air. What is the direction of force?

A. away from 1c
B. away from -4c
C. from 1c to -4c
D. from -4c to 1c
Answer» C. from 1c to -4c
49.

The Coulomb law is an implication of which law?

A. ampere law
B. gauss law
C. biot savart law
D. lenz law
Answer» B. gauss law
50.

For a charge Q1, the effect of charge Q2 on Q1 will be,

A. f1 = f2
B. f1 = -f2
C. f1 = f2 = 0
D. f1 and f2 are not equal
Answer» B. f1 = -f2
51.

The electric field intensity is defined as

A. force per unit charge
B. force on a test charge
C. force per unit charge on a test charge
D. product of force and charge
Answer» C. force per unit charge on a test charge
52.

Find the force on a charge 2C in a field 1V/m.

A. 0
B. 1
C. 2
D. 3
Answer» C. 2
53.

Electric field intensity due to infinite sheet of charge σ is

A. zero
B. unity
C. σ/ε
D. σ/2ε
Answer» D. σ/2ε
54.

For a test charge placed at infinity, the electric field will be

A. unity
B. +∞
C. zero
D. -∞
Answer» C. zero
55.

The lines of force are said to be

A. real
B. imaginary
C. drawn to trace the direction
D. not significant
Answer» C. drawn to trace the direction
56.

Electric flux density in electric field is referred to as

A. number of flux lines
B. ratio of flux lines crossing a surface and the surface area
C. direction of flux at a point
D. flux lines per unit area
Answer» B. ratio of flux lines crossing a surface and the surface area
57.

The electric flux density is the

A. product of permittivity and electric field intensity
B. product of number of flux lines and permittivity
C. product of permeability and electric field intensity
D. product of number of flux lines and permeability
Answer» A. product of permittivity and electric field intensity
58.

Which of the following correctly states Gauss law?

A. electric flux is equal to charge
B. electric flux per unit volume is equal to charge
C. electric field is equal to charge density
D. electric flux per unit volume is equal to volume charge density
Answer» D. electric flux per unit volume is equal to volume charge density
59.

The Gaussian surface is

A. real boundary
B. imaginary surface
C. tangential
D. normal
Answer» B. imaginary surface
60.

A point charge 2nC is located at origin. What is the potential at (1,0,0)?

A. 12
B. 14
C. 16
D. 18
Answer» D. 18
61.

Find the potential of V = 60sin θ/r2 at P(3,60,25)

A. 5.774
B. 6.774
C. 7.774
D. 8.774
Answer» A. 5.774
62.

The potential difference in an open circuit is

A. zero
B. unity
C. infinity
D. circuit does not exist open
Answer» C. infinity
63.

The potential taken between two points across a resistor will be

A. positive
B. negative
C. zero
D. infinity
Answer» B. negative
64.

What is the potential difference between 10sinθcosφ/r2 at A(1,30,20) and B(4,90,60)?

A. 2.386
B. 3.386
C. 4.386
D. 5.386
Answer» C. 4.386
65.

The voltage at any point in an ac circuit will be

A. peak voltage
B. rms voltage
C. average voltage
D. source voltage
Answer» B. rms voltage
66.

Divergence theorem is based on

A. gauss law
B. stoke’s law
C. ampere law
D. lenz law
Answer» A. gauss law
67.

The Gaussian surface for a line charge will be

A. sphere
B. cylinder
C. cube
D. cuboid
Answer» B. cylinder
68.

The Gaussian surface for a point charge will be

A. cube
B. cylinder
C. sphere
D. cuboid
Answer» C. sphere
69.

The total charge of a surface with densities 1,2,…,10 is

A. 11
B. 33
C. 55
D. 77
Answer» C. 55
70.

The work done by a charge of 10μC with a potential 4.386 is (in μJ)

A. 32.86
B. 43.86
C. 54.68
D. 65.68
Answer» B. 43.86
71.

Gauss law cannot be used to find which of the following quantity?

A. electric field intensity
B. electric flux density
C. charge
D. permittivity
Answer» D. permittivity
72.

Gauss law for magnetic fields is given by

A. div(e) = 0
B. div(b) = 0
C. div(h) = 0
D. div(d) = 0
Answer» B. div(b) = 0
73.

Gauss law can be used to compute which of the following?

A. permittivity
B. permeability
C. radius of gaussian surface
D. electric potential
Answer» C. radius of gaussian surface
74.

Gauss law can be evaluated in which coordinate system?

A. cartesian
B. cylinder
C. spherical
D. depends on the gaussian surface
Answer» D. depends on the gaussian surface
75.

Gauss law cannot be expressed in which of the following forms?

A. differential
B. integral
C. point
D. stokes theorem
Answer» D. stokes theorem
76.

With Gauss law as reference which of the following law can be derived?

A. ampere law
B. faraday’s law
C. coulomb’s law
D. ohm’s law
Answer» C. coulomb’s law
77.

The electric flux density and electric field intensity have which of the following relation?

A. linear
B. nonlinear
C. inversely linear
D. inversely nonlinear
Answer» A. linear
78.

Find the potential at a point (4, 3, -6) for the function V = 2x2y + 5z.

A. 96
B. 66
C. 30
D. -66
Answer» B. 66
79.

Find the potential of the function V = 60cos θ/r at the point P(3, 60, 25).

A. 20
B. 10
C. 30
D. 60
Answer» B. 10
80.

Find the work done moving a charge 2C having potential V = 24volts is

A. 96
B. 24
C. 36
D. 48
Answer» D. 48
81.

The distance vector is obtained in

A. cartesian coordinate system
B. spherical coordinate system
C. circular coordinate system
D. space coordinate system
Answer» D. space coordinate system
82.

The divergence of distance vector is

A. 0
B. 3
C. 2
D. 1
Answer» B. 3
83.

Find a vector normal to a plane consisting of points p1(0,1,0), p2(1,0,1) and p3(0,0,1)

A. –j – k
B. –i – j
C. –i – k
D. –i – j – k
Answer» A. –j – k
84.

The unit vector to the points p1(0,1,0), p2(1,0,1), p3(0,0,1) is

A. (-j – k)/1.414
B. (-i – k)/1.414
C. (-i – j)/1.414
D. (-i – j – k)/1.414
Answer» A. (-j – k)/1.414
85.

The polar form of Cartesian coordinates is

A. circular coordinates
B. spherical coordinates
C. cartesian coordinates
D. space coordinates
Answer» A. circular coordinates
86.

The work-electric field relation is given by

A. volume integral
B. surface integral
C. line integral
D. relation impossible
Answer» C. line integral
87.

The distance vector can be used to compute which of the following?

A. dot product
B. cross product
C. unit normal vector
D. area
Answer» C. unit normal vector
88.

Distance and position vectors rely on field strength. State True/False.

A. true
B. false
Answer» A. true
89.

Find the projection of A on B. Given A = 10j + 3k and B = 4j + 5k.

A. 6
B. 6.25
C. 6.5
D. 6.75
Answer» B. 6.25
90.

The del operator is called as

A. gradient
B. curl
C. divergence
D. vector differential operator
Answer» D. vector differential operator
91.

The relation between vector potential and field strength is given by

A. gradient
B. divergence
C. curl
D. del operator
Answer» A. gradient
92.

The Laplacian operator is actually

A. grad(div v)
B. div(grad v)
C. curl(div v)
D. div(curl v)
Answer» B. div(grad v)
93.

The divergence of curl of a vector is zero. State True or False.

A. true
B. false
Answer» A. true
94.

The curl of gradient of a vector is non-zero. State True or False.

A. true
B. false
Answer» B. false
95.

Identify the correct vector identity.

A. i . i = j . j = k . k = 0
B. i x j = j x k = k x i = 1
C. div (u x v) = v . curl(u) – u . curl(v)
D. i . j = j . k = k . i = 1
Answer» C. div (u x v) = v . curl(u) – u . curl(v)
96.

A vector is said to be solenoidal when its

A. divergence is zero
B. divergence is unity
C. curl is zero
D. curl is unity
Answer» A. divergence is zero
97.

The magnetic field intensity is said to be

A. divergent
B. curl free
C. solenoidal
D. rotational
Answer» C. solenoidal
98.

A field has zero divergence and it has curls. The field is said to be

A. divergent, rotational
B. solenoidal, rotational
C. solenoidal, irrotational
D. divergent, irrotational
Answer» B. solenoidal, rotational
99.

When a vector is irrotational, which condition holds good?

A. stoke’s theorem gives non-zero value
B. stoke’s theorem gives zero value
C. divergence theorem is invalid
D. divergence theorem is valid
Answer» B. stoke’s theorem gives zero value
100.

The Cartesian system is also called as

A. circular coordinate system
B. rectangular coordinate system
C. spherical coordinate system
D. space coordinate system
Answer» B. rectangular coordinate system
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