# Multiple choice question for engineering

## Set 1

1. Find the electric force when the charge of 2C is subjected to an electric field of 6 units.

a) 6

b) 3

c) 12

d) 24

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2. Find the magnetic force when a charge 3.5C with flux density of 4 units is having a velocity of 2m/s.

a) 14

b) 28

c) 7

d) 32

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3. Find the electric field when the velocity of the field is 12m/s and the flux density is 8.75 units.

a) 510

b) 105

c) 150

d) 165

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4. Find the Lorentz force of a charge 2.5C having an electric field of 5 units and magnetic field of 7.25 units with a velocity 1.5m/s.

a) 39.68

b) 68.39

c) 86.93

d) 93.68

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5. The force on a conductor of length 12cm having current 8A and flux density 3.75 units at an angle of 300 is

a) 1.6

b) 2

c) 1.4

d) 1.8

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6. The force per unit length of two conductors carrying equal currents of 5A separated by a distance of 20cm in air(in 10^{-6} order)

a) 25

b) 35

c) 40

d) 50

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^{-7}x 52/ 2π x 0.2 = 25 x 10

^{-6}units.

7. When currents are moving in the same direction in two conductors, then the force will be

a) Attractive

b) Repulsive

c) Retracting

d) Opposing

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8. Find the flux density due to a conductor of length 6m and carrying a current of 3A(in 10^{-7} order)

a) 1

b) 10

c) 100

d) 0.1

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^{-7}x 3/2π x 6 = 1 x 10

^{-7}units.

9. Find the maximum force of the conductor having length 60cm, current 2.75A and flux density of 9 units.

a) 14.85

b) 18.54

c) 84.25

d) 7.256

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10. The magnetic force impacts the energy of the field. State True/false.

a) True

b) False

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^{2}/μ. It is clear that B and F are related.

## Set 2

1. In a waveguide, which of the following condition is true always?

a) phase velocity = c

b) group velocity = c

c) phase velocity > c

d) phase velocity < c

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2. The term cos θ is given by 2.5. Find the phase velocity.

a) 3

b) 5

c) 7.5

d) 2.5

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^{8}m/s.

3. The cut off wavelength and the guided wavelength are given by 0.5 and 2 units respectively. Find the wavelength of the wave.

a) 0.48

b) 0.32

c) 0.45

d) 0.54

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^{2}= (1/λc)

^{2}+ (1/λg)

^{2}. On substituting for λc = 0.5 and λg = 2, we get λ = 0.48 units.

4. The cut off wavelength of the rectangular waveguide in dominant mode with dimensions 6 cm x 4 cm is

a) 12cm

b) 6cm

c) 4cm

d) 2cm

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5. The product of the phase and the group velocities is given by the

a) Speed of light

b) Speed of light/2

c) 2 x Speed of light

d) (speed of light)/4

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^{2}is the relation.

6. The phase velocity of a wave having a group velocity of 6 x 10^{6} is (in order of 10^{8} m/s)

a) 2.4

b) 3

c) 15

d) 150

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^{2}. On substituting for Vg = 6 x 10

^{6}and the speed of light, we get Vp = 150 x 10

^{8}m/s.

7. The group velocity of a wave with a phase velocity of 60 x 10^{9} is (in 10^{6} order)

a) 1.5

b) 2

c) 2.5

d) 3

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^{2}. On substituting for Vp = 60 x 10

^{9}and the speed of light, we get Vg = 1.5 x 10

^{6}m/s.

8. The phase velocity of a wave having a phase constant of 4 units and a frequency of 2.5 x 10^{9} radian/sec is (in 10^{8} order)

a) 3.25

b) 3.75

c) 6.25

d) 6.75

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^{9}and β = 4, we get the phase velocity as 6.25 units.

9. The guided wavelength and the phase constant are related by

a) 2π/βg = λg

b) 1/βg = λg

c) 1/2πβg = λg

d) βg = λg

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10. The phase velocity refers to a group of waves and the group velocity refers to a single wave. State true/false.

a) True

b) False

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11. The phase and group velocities does not depend on which of the following?

a) Frequency

b) Wavelength

c) Phase constant

d) Attenuation constant

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12. The distance between two successive points in a waveguide is the

a) Guided wavelength

b) 2 x guided wavelength

c) Guided wavelength/2

d) (guided wavelength)/4

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## Set 3

1. In free space, the charge carriers will be

a) 0

b) 1

c) 100

d) Infinity

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2. In free space, which parameter will be unity?

a) Permittivity

b) Absolute permittivity

c) Relative permittivity

d) Permeability

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^{-12}C/m2.

3. Which parameter is unity in air medium?

a) Permittivity

b) Absolute permeability

c) Relative permeability

d) Permeability

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^{-7}units.

4. The conductivity in free space medium is

a) Infinity

b) Unity

c) Zero

d) Negative

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5. Zero permeability/permittivity implies which state?

a) No ions are allowed in the medium

b) No current is generated in the medium

c) No magnetic or electric energy is permitted in the medium

d) No resistivity

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6. The intrinsic impedance of free space is

a) 489

b) 265

c) 192

d) 377

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^{-7}and absolute permittivity is given by 8.854 x 10

^{-12}. The intrinsic impedance will be 377 ohms.

7. In free space, the condition that holds good is

a) Minimum attenuation and propagation

b) Minimum attenuation and maximum propagation

c) Maximum attenuation and minimum propagation

d) Maximum attenuation and propagation

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8. In free space, the ratio of frequency to the velocity of light gives the phase constant. State True/False.

a) True

b) False

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9. The velocity of a wave travelling in the air medium without transmission lines or waveguides(wireless) is

a) 6 x 10^{8}

b) 3 x 10^{8}

c) 1.5 x 10^{8}

d) 9 x 10^{8}

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^{8}m/s.

10. The vectors of the electromagnetic wave propagation can be expressed in

a) Dot product

b) Cross product

c) Unit vector

d) Perpendicular vector

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## Set 4

1. For conductors, the loss tangent will be

a) Zero

b) Unity

c) Maximum

d) Minimum

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2. In metals, the total permittivity is

a) Absolute permittivity

b) Relative permittivity

c) Product of absolute and relative permittivity

d) Unity

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3. The total permeability in a conductor is

a) Absolute permeability

b) Relative permeability

c) Product of absolute and relative permeability

d) Unity

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4. Calculate the phase constant of a conductor with attenuation constant given by 0.04 units.

a) 0.02

b) 0.08

c) 0.0016

d) 0.04

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5. Calculate the attenuation constant of a conductor of conductivity 200 units, frequency 1M radian/s in air.

a) 11.2

b) 1.12

c) 56.23

d) 5.62

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^{6}, σ = 200 and μ = 4π x 10

^{-7}, we get α = 11.2 units.

6. The skin depth of a conductor with attenuation constant of 7 neper/m is

a) 14

b) 49

c) 7

d) 1/7

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7. The expression for velocity of a wave in the conductor is

a) V = √(2ω/μσ)

b) V = √(2ωμσ)

c) V = (2ω/μσ)

d) V = (2ωμσ)

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8. In conductors, the E and H vary by a phase difference of

a) 0

b) 30

c) 45

d) 60

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9. EM waves do not travel inside metals. State True/False.

a) True

b) False

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10. The propagation constant of the wave in a conductor with air as medium is

a) √(ωμσ)

b) ωμσ

c) √(ω/μσ)

d) ω/μσ

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11. An example for electromagnetic wave propagation is

a) refrigerator

b) electric fan

c) mobile transponder

d) relays in actuators

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12. The phase shift in the electric and magnetic fields in an EM wave is given by which parameter?

a) phase constant

b) attenuation constant

c) propagation constant

d) intrinsic impedance

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## Set 5

1. The total power of a wave with average power 15 units in a surface density of 0.5 units is

a) 15

b) 30

c) 7.5

d) 0.75

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2. The power of a wave with electric field intensity of 3 units in air is

a) 0.01

b) 0.03

c) 0.05

d) 0.07

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^{2}/2η. On substituting for E = 3 and η = 377 in air, the power is P = 3

^{2}/(2×377) = 0.01 units.

3. Find the power of an EM wave, given that the cross product of the E and H component is 2 + 3j.

a) 2

b) 1

c) 4

d) 8

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4. The power in a electromagnetic wave with electric field and magnetic field intensities 12 and 8 respectively is

a) 96

b) 12

c) 8

d) 48

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5. The power in a wave given that H component is 0.82 units in air.

a) 126.74

b) 621.47

c) 216.47

d) 745.62

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^{2}/2. In air medium, η = 377 and given that H = 0.82. We get power P = 377 x 0.82

^{2}/2 = 126.74 units.

6. Find the power of a wave given that the RMS value of E and H are 6 and 4.5 respectively.

a) 24

b) 27

c) 29

d) 32

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7. The electric and magnetic fields vary with time in which of the following fields?

a) DC

b) AC

c) Static

d) It does not vary with time

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8. The power per unit velocity of a wave with electric field as 8 units and density 10 units is

a) 40

b) 20

c) 80

d) 160

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9. The power of a wave in a cylindrical waveguide of radius 2m with electric field 12 units is

a) 2.39

b) 3.92

c) 9.23

d) 9.32

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^{2}/2η and ∫ds = πr

^{2}. On substituting for E = 12, η = 377 in air and r = 2, we get P = 2.39 units.

10. The work done in the power transmission with E and H given by 50 and 65 respectively. The velocity of propagation is 20m/s.

a) 162.5

b) 621.5

c) 562.1

d) 261.5

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11. The Poynting vector is the power component that is calculated by the

a) Product of E and H

b) Ratio of E and H

c) Dot product of E and H

d) Cross product of E and H

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12. The maximum power transceived by the antenna is in the region of

a) Aperture

b) Effective aperture

c) Maxima lobe

d) Minima lobe