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Test: Plane Waves in Good Conductor & Dielectrics - Electrical Engineering (EE) MCQ


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24 Questions MCQ Test Electromagnetic Fields Theory (EMFT) - Test: Plane Waves in Good Conductor & Dielectrics

Test: Plane Waves in Good Conductor & Dielectrics for Electrical Engineering (EE) 2024 is part of Electromagnetic Fields Theory (EMFT) preparation. The Test: Plane Waves in Good Conductor & Dielectrics questions and answers have been prepared according to the Electrical Engineering (EE) exam syllabus.The Test: Plane Waves in Good Conductor & Dielectrics MCQs are made for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Plane Waves in Good Conductor & Dielectrics below.
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Test: Plane Waves in Good Conductor & Dielectrics - Question 1

For conductors, the loss tangent will be

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 1

Answer: c
Explanation: In conductors, the conductivity will be more. Thus the loss tangent σ/ωε will be maximum.

Test: Plane Waves in Good Conductor & Dielectrics - Question 2

In metals, the total permittivity is

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 2

Answer: a
Explanation: The total permittivity is the product of the absolute and the relative permittivity. For metals or conductors, the relative permittivity is unity. Thus the permittivity is simply the absolute permittivity.

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Test: Plane Waves in Good Conductor & Dielectrics - Question 3

The total permeability in a conductor is

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 3

Answer: c
Explanation: The total permeability is the product of the absolute and the relative permeability. For metals or conductors, the relative permittivity is not unity. Thus the permittivity is the product of absolute and relative permeability.

Test: Plane Waves in Good Conductor & Dielectrics - Question 4

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 4

Answer: d
Explanation: The phase constant and the attenuation constant are both the same in the case of conductors. Given that the attenuation constant is 0.04, implies that the phase constant is also 0.04.

Test: Plane Waves in Good Conductor & Dielectrics - Question 5

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 5

Answer: a
Explanation: The attenuation constant of a conductor is given by α = √(ωμσ/2). On substituting ω = 106, σ = 200 and μ = 4π x 10-7, we get α = 11.2 units.

Test: Plane Waves in Good Conductor & Dielectrics - Question 6

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 6

Answer: d
Explanation: The skin depth is the measure of the depth upto which an EM wave can penetrate through the conductor surface. It is the reciprocal of the attenuation constant. On substituting for α = 7, we get δ = 1/α = 1/7 units.

Test: Plane Waves in Good Conductor & Dielectrics - Question 7

The expression for velocity of a wave in the conductor is

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 7

Answer: a
Explanation: The velocity is the ratio of the frequency to the phase constant. In conductors, the phase constant is given by √(ωμσ/2). On substituting for β,ω in v, we get v = √(2ω/μσ) units

Test: Plane Waves in Good Conductor & Dielectrics - Question 8

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 8

Answer: c
Explanation: The electric and magnetic component, E and H respectively have a phase difference of 45 degrees. This is due to the wave propagation in conductors in the air medium.

Test: Plane Waves in Good Conductor & Dielectrics - Question 9

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 9

Answer: a
Explanation: The conductors or metals do not support EM wave propagation onto them due the skin effect. This is the reason why mobile phones cannot be used inside lifts.

Test: Plane Waves in Good Conductor & Dielectrics - Question 10

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 10

Answer: a
Explanation: The propagation constant is the sum of the attenuation constant and the phase constant. In conductors, the attenuation and phase constant both are same and it is given by √(ωμσ/2). Their sum will be √(ωμσ), is the propagation constant.

Test: Plane Waves in Good Conductor & Dielectrics - Question 11

An example for electromagnetic wave propagation is

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 11

Answer: c
Explanation: The refrigerator, electric fan and relays are electrical devices. They do not use electromagnetic energy as medium of energy transfer. The mobile transponder is an antenna, which uses the EM waves for communication with the satellites.

Test: Plane Waves in Good Conductor & Dielectrics - Question 12

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 12

Answer: d
Explanation: The intrinsic impedance in a conductor is given by η = √(ωμ/2σ) x (1+j). The phase shift is represented by the 1+j term. In polar form it indicates 45 degree phase shift.

Test: Plane Waves in Good Conductor & Dielectrics - Question 13

The loss tangent of a perfect dielectric will be

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 13

Answer: d
Explanation: Dielectrics have poor conductivity. The loss tangent σ/ωε will be low in dielectrics. For perfect dielectrics, the loss tangent will be minimum.

Test: Plane Waves in Good Conductor & Dielectrics - Question 14

In pure dielectrics, the parameter that is zero is

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 14

Answer: c
Explanation: There are no free charge carriers available in a dielectric. In other words, the charge carriers are present in the valence band, which is very difficult to start to conduct. Thus conduction is low in dielectrics. For pure dielectrics, the conductivity is assumed to be zero.

Test: Plane Waves in Good Conductor & Dielectrics - Question 15

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 15

Answer: a
Explanation: The total permittivity is the product of the absolute and the relative permittivity. The absolute permittivity is 8.854 x 10-12 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.

Test: Plane Waves in Good Conductor & Dielectrics - Question 16

The permeability of a dielectric material in air medium will be

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 16

Answer: a
Explanation: The total permeability is the product of the absolute and the relative permeability. In air medium, the relative permeability will be unity. Thus the total permeability is equal to the absolute permeability given by 4π x 10-7 units.

Test: Plane Waves in Good Conductor & Dielectrics - Question 17

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 17

Answer: a
Explanation: Good dielectrics attenuate the electromagnetic waves than any other material. Thus the attenuation constant of the dielectric will be non-zero, positive and large.

Test: Plane Waves in Good Conductor & Dielectrics - Question 18

Calculate the phase constant of a dielectric with frequency 6 x 106 in air. 

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 18

Answer: c
Explanation: The phase constant of a dielectric is given by β = ω√(με). On substituting for ω = 6 x 106 , μ = 4π x 10-7, ε = 8.854 x 10-12 in air medium, we get the phase constant as 0.02 units.

Test: Plane Waves in Good Conductor & Dielectrics - Question 19

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 19

Answer: a
Explanation: The velocity of a wave is given by V = ω/β. To get ω, put v = 3 x 108 and β = 20. Thus ω = vβ = 3 x 108 x 20 = 60 x 108 = 6 GHz.

Test: Plane Waves in Good Conductor & Dielectrics - Question 20

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 20

Answer: a
Explanation: The standard relation between speed of light, permeability and permittivity is given by c = 1/√(με). The value in air medium is 3 x 108 m/s.

Test: Plane Waves in Good Conductor & Dielectrics - Question 21

The phase constant of a wave with wavelength 2 units is

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 21

Answer: b
Explanation: The phase constant is given by β = 2π/λ. On substituting λ = 2 units, we get β = 2π/2 = π = 3.14 units.

Test: Plane Waves in Good Conductor & Dielectrics - Question 22

The expression for intrinsic impedance is given by

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 22

Answer: c
Explanation: The intrinsic impedance is given by the ratio of square root of the permittivity to the permeability. Thus η = √(μ/ε) is the intrinsic impedance. In free space or air medium, the intrinsic impedance will be 120π or 377 ohms.

Test: Plane Waves in Good Conductor & Dielectrics - Question 23

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 23

Answer: a
Explanation: In dielectrics, the electric and magnetic fields will be in phase or the phase difference between them is zero. This is due to the large attenuation which leads to increase in phase shift.

Test: Plane Waves in Good Conductor & Dielectrics - Question 24

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

Detailed Solution for Test: Plane Waves in Good Conductor & Dielectrics - Question 24

Answer: b
Explanation: The skin depth is the reciprocal of the phase constant. On substituting for β = 12, we get δ = 1/β = 1/12 units.

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