Electromagnetic Theory Questions and Answers – Intrinsic Impedance and Propagation Constant

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This set of Electromagnetic Theory Questions and Answers for Aptitude test focuses on “Intrinsic Impedance and Propagation Constant”.

1. The intrinsic impedance of a wave with electric and magnetic field of 10 and 8 respectively is
a) 1.6
b) 1.11
c) 1.25
d) 0.8
View Answer

Answer: b
Explanation: The intrinsic impedance of a wave is given by η = √(E/H). on substituting for E = 10 and H = 8, we get η = 1.11 units.
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2. The intrinsic impedance is defined as the ratio of the magnetic field to the electric field of the electromagnetic wave. State true/false
a) True
b) False
View Answer

Answer: b
Explanation: The intrinsic impedance is defined as the ratio of the electric field intensity to the magnetic field intensity. It is denoted by η. It is a complex quantity.

3. The intrinsic impedance in free space is
a) 60π
b) 12π
c) 6π
d) 120π
View Answer

Answer: d
Explanation: The intrinsic impedance of the free space is the ratio of the permittivity to the permeability. For air medium, the value is 120π or 377 ohm.
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4. The propagation constant is a complex quantity. State true/false.
a) True
b) False
View Answer

Answer: a
Explanation: The propagation constant is a complex quantity. It is given by γ = α + jβ, where α is the attenuation constant, a real value and β is the phase constant, a complex value.

5. Calculate the propagation constant of a wave with impedance and admittance given by 32 and 12 respectively.
a) 19.6
b) 17.6
c) 15.6
d) 13.6
View Answer

Answer: a
Explanation: The propagation constant is given by γ = √(ZY), where Z is the impedance and Y is the admittance. On substituting for Z = 32 and Y = 12, we get γ = 19.6 units.
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6. The intrinsic angle is 250, find the loss angle.
a) 12.5
b) 50
c) 25
d) 75
View Answer

Answer: b
Explanation: The loss angle is twice of the intrinsic angle. It is given by δ = 2θn. On substituting for θn = 25, the loss angle δ = 2(25) = 50 degree.

7. The standing wave ratio of the wave with maximum and minimum electric field intensities of 12 and 4 is
a) 12
b) 4
c) 3
d) 48
View Answer

Answer: c
Explanation: The SWR is defined as the ratio of maximum electric field intensities to the minimum field intensities. It is given by S = EMAX/EMIN. Thus for the given data, S = 12/4 = 3.
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8. The standing wave ratio of a wave travelling through two media having intrinsic impedances of 3 and 2 is
a) 23
b) 32
c) 15
d) 5
View Answer

Answer: b
Explanation: The standing wave ratio is given by the ratio of the intrinsic impedance of medium 1 to the intrinsic impedance of medium 2. Thus S = η1/η2. On substituting for η1 = 3 and η2 = 2, we get S = 3/2.

9. The reflection coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 5 respectively is
a) 2
b) 8
c) 53
d) 1/4
View Answer

Answer: d
Explanation: The reflection coefficient in terms for intrinsic impedance is R= η2-η1/η2+η1. On substituting the given data, we get R = 5 – 3/5 + 3 = 2/8 = ¼.
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10. The reflection coefficient of a wave travelling through two media having magnetic intrinsic impedances of 2 and 1 respectively is
a) 12
b) 13
c) 14
d) 15
View Answer

Answer: b
Explanation: The reflection coefficient in terms for magnetic intrinsic impedance is R = η1 – η2/η1 + η2. On substituting the given data, we get R = 2 – 1/2 + 1 = 1/3.

11. The transmission coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 2 respectively is
a) 22
b) 89
c) 45
d) 14
View Answer

Answer: c
Explanation: The transmission coefficient in terms for intrinsic impedance is R = 2η2/η2 + η1. On substituting the given data, we get R = 2 x 2/2 + 3 = 4/5.

12. The transmission coefficient of a wave travelling through two media having electric intrinsic impedances of 3 and 4 respectively is
a) 23
b) 89
c) 25
d) 67
View Answer

Answer: d
Explanation: The transmission coefficient in terms for intrinsic impedance is R = 2η1/η2 + η1. On substituting the given data, we get R = 2 x 34 + 3 = 6/7.

Sanfoundry Global Education & Learning Series – Electromagnetic Theory.
To practice all areas of Electromagnetic Theory for Aptitude test, here is complete set of 1000+ Multiple Choice Questions and Answers.

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