# Multiple choice question for engineering

## Set 1

1. Find the correct relation between current density and magnetization.

a) J = Grad(M)

b) J = Div(M)

c) J = Curl(M)

d) M = Curl(J)

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2. The tangential component of the magnetic field intensity is continuous at the boundary of separation of two media. State True/False.

a) True

b) False

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3. In air, the tangential component of flux density is continuous at the boundary. State True/False.

a) True

b) False

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4. The flux density of medium 1 has a normal component of 2.4 units, then the normal component of the flux density in the medium 2 will be

a) 1.2

b) 4.8

c) 2.4

d) 0

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5. The normal component of magnetic field intensity at the boundary of separation of the medium will be

a) Same

b) Different

c) Negative

d) Inverse

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6. The line integral of the magnetic field intensity is the

a) Current density

b) Current

c) Magnetic flux density

d) Magnetic moment

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7. Find the magnetization of the material with susceptibility of 6 units and magnetic field intensity of 13 units.

a) 2.16

b) 6.2

c) 78

d) 1.3

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8. Find the ratio of permeability of the two media when the wave is incident on the boundary at 45 degree and reflected by the boundary at 60 degree.

a) 1:1

b) √3:1

c) 1:√3

d) 1:√2

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9. Find the magnetic moment of a material with magnetization 5 units in a volume of 35 units.

a) 7

b) 1/7

c) 15

d) 175

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10. A boundary of separation between two magnetic materials is identified by which factor?

a) Change in the permeability

b) Change in permittivity

c) Change in magnetization

d) Conduction

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## Set 2

1. The distance vector is obtained in

a) Cartesian coordinate system

b) Spherical coordinate system

c) Circular coordinate system

d) Space coordinate system

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2. The divergence of distance vector is

a) 0

b) 3

c) 2

d) 1

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3. 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

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4. 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

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5. The polar form of Cartesian coordinates is

a) Circular coordinates

b) Spherical coordinates

c) Cartesian coordinates

d) Space coordinates

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6. The work-electric field relation is given by

a) Volume integral

b) Surface integral

c) Line integral

d) Relation impossible

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

a) Dot product

b) Cross product

c) Unit normal vector

d) Area

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

a) True

b) False

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9. 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

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10. The vector product of two vectors is given by area of the parallelogram. State True/False.

a) True

b) False

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## Set 3

1. Identify the advantage of using method of images.

a) Easy approach

b) Boundaries are replaced by charges

c) Boundaries are replaced by images

d) Calculation using Poisson and Laplace equation

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2. Calculate the electric field intensity of a line charge of length 2m and potential 24V.

a) 24

b) 12

c) 0.083

d) 12.67

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3. Calculate potential of a metal plate of charge 28C and capacitance 12 mF.

a) 3.33 kohm

b) 2.33 kohm

c) 3.33 Mohm

d) 2.33 Mohm

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^{-3}= 2.333 x 10

^{3}ohm.

4. Find the dissipation factor when series resistance is 5 ohm and capacitive resistance is 10 unit.

a) 2

b) 0.5

c) 1

d) 0

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5. A material with zero resistivity is said to have

a) Zero conductance

b) Infinite conductance

c) Zero resistance

d) Infinite resistance

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6. Find the energy stored by the capacitor 3F having a potential of 12V across it.

a) 432

b) 108

c) 216

d) 54

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^{2}. E = 0.5 x 3 x 12

^{2}= 0.5 x 432 = 216 units.

7. By method of images, the problem can be easily calculated by replacing the boundary with which polygon?

a) Rectangle

b) Trapezoid

c) Square

d) Triangle

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8. Calculate the electric field due to a surface charge of 20 units on a plate in air(in 10^{12} order)

a) 2.19

b) 1.12

c) 9.21

d) 2.91

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^{-12}) = 1.129 x 10

^{12}units.

9. Find the electric field due to charge density of 1/18 and distance from a point P is 0.5 in air(in 10^{9} order)

a) 0

b) 1

c) 2

d) 3

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^{9}units.

10. Find the total capacitances when two capacitors 2F and 5F are in series.

a) 5/7

b) 12/7

c) 2/5

d) 10/7

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## Set 4

1. The del operator is called as

a) Gradient

b) Curl

c) Divergence

d) Vector differential operator

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2. The relation between vector potential and field strength is given by

a) Gradient

b) Divergence

c) Curl

d) Del operator

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3. The Laplacian operator is actually

a) Grad(Div V)

b) Div(Grad V)

c) Curl(Div V)

d) Div(Curl V)

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^{2}V operator.

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

a) True

b) False

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

a) True

b) False

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6. 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

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7. 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

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8. The magnetic field intensity is said to be

a) Divergent

b) Curl free

c) Solenoidal

d) Rotational

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9. 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

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10. 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

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## Set 5

1. The loss tangent of a perfect dielectric will be

a) Zero

b) Unity

c) Maximum

d) Minimum

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2. In pure dielectrics, the parameter that is zero is

a) Attenuation

b) Propagation

c) Conductivity

d) Resistivity

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3. The total permittivity of a dielectric transformer oil (relative permittivity is 2.2) will be (in order 10^{-11})

a) 1.94

b) 19.4

c) 0.194

d) 194

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^{-12}and the relative permittivity(in this case for transformer oil) is 2.2. Thus the total permittivity is 8.854 x 10

^{-12}x 2.2 = 1.94 x 10

^{-11}units.

4. The permeability of a dielectric material in air medium will be

a) Absolute permeability

b) Relative permeability

c) Product of absolute and relative permeability

d) Unity

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^{-7}units.

5. The attenuation in a good dielectric will be non- zero. State True/False.

a) True

b) False

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6. Calculate the phase constant of a dielectric with frequency 6 x 10^{6} in air.

a) 2

b) 0.2

c) 0.02

d) 0.002

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^{6}, μ = 4π x 10

^{-7}, ε = 8.854 x 10

^{-12}in air medium, we get the phase constant as 0.02 units.

7. The frequency in rad/sec of a wave with velocity of that of light and phase constant of 20 units is (in GHz)

a) 6

b) 60

c) 600

d) 0.6

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^{8}and β = 20. Thus ω = vβ = 3 x 10

^{8 x 20 = 60 x 108 = 6 GHz.}

8. The relation between the speed of light, permeability and permittivity is

a) C = 1/√(με)

b) C = με

c) C = μ/ε

d) C = 1/με

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^{8}m/s.

9. The phase constant of a wave with wavelength 2 units is

a) 6.28

b) 3.14

c) 0.5

d) 2

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10.The expression for intrinsic impedance is given by

a) √(με)

b) (με)

c) √(μ/ε)

d) (μ/ε)

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11.The electric and magnetic field components in the electromagnetic wave propagation are in phase. State True/False.

a) True

b) False

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12. The skin depth of a wave with phase constant of 12 units inside a conductor is

a) 12

b) 1/12

c) 24

d) 1/24