Electromagnetic Field Theory MCQ Questions & Answers

21

Which one of the following statements does not pertain to the equation?
$$\nabla .\overrightarrow {\text{B}} = 0?$$

A) There are no sinks and sources for magnetic fields B) Magnetic field is perpendicular to the electric field C) Single magnetic pole, cannot exist D) B is solenoidal

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Answer & Solution

Answer: Option B

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22

The magnitude of reflection coefficient is:

A) $$\left| \rho \right| = \frac{{{{\text{v}}_{\max }}}}{{{{\text{v}}_{\min }}}}$$ B) $$\left| \rho \right| = \frac{{\left( {{\text{VSWR}} - 1} \right)}}{{\left( {{\text{VSWR}} + 1} \right)}}$$ C) $$\left| \rho \right| = \frac{{\left( {{\text{VSWR}} + 1} \right)}}{{\left( {{\text{VSWR}} - 1} \right)}}$$ D) $$\left| \rho \right| = \frac{{\left| {{{\text{v}}_{\text{i}}}} \right|}}{{\left| {{{\text{v}}_{\text{r}}}} \right|}}$$

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Answer & Solution

Answer: Option B

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23

A 75 ohm transmission line is to be terminated in two resistive loads R₁ and R₂ such that the standing patterns in the two cases have the same SWR. To obtain the desired result, the values of R₁ and R₂ (in ohms) should be

A) 250 and 200 respectively B) 225 and 25 respectively C) 100 and 150 respectively D) 50 and 125 respectively

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Answer & Solution

Answer: Option B

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24

Two lossy lines are to be joined end to end. The first line is 10 m long and has a loss rating of 0.20 dB/m. The second lines is 15 m long and has a loss rating of 0.10 dB/m. The reflection coefficient at the junction (line 1 to line 2) is Γ = 0.30. The input power (to line 1) is 100 mW. Determine the total loss of the combination in dB to the output end of line 2.

A) 3.91 dB B) 2.91 dB C) 4.91 dB D) 1.91 dB

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Answer & Solution

Answer: Option A

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25

The potential (scalar) distribution is given as V = 10y⁴ + 20x³. If ε₀ is the permittivity of free space, what is the charge density ρ at the point (2, 0)?

A) -200ε₀ B) -200/ε₀ C) 200ε₀ D) -240ε₀

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Answer & Solution

Answer: Option D

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26

A plane wave propagating in the dielectric medium has an electric field given as E_x = E₀ Cos(2.6 × 10¹⁰t - 100z). The phase velocity of plane wave is:

A) 10⁶ m/sec B) 2.6 × 10⁸ m/sec C) 3.0 × 10⁸ m/sec D) 4.0 × 10⁸ m/sec

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Answer & Solution

Answer: Option B

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27

Given potential V = 2x²y + z², then the electric field at (1, 1, 0) is

A) $$ - 4{{\hat a}_x} - 2{{\hat a}_y}$$ B) $$4{{\hat a}_x} + 2{{\hat a}_y}$$ C) $$ - 2{{\hat a}_x} - 4{{\hat a}_y}$$ D) $$2{{\hat a}_x} + 4{{\hat a}_y}$$

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Answer & Solution

Answer: Option A

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28

Maxwell's major contribution to EM theory was to assert

A) that an electric field varying with time in free space gives rise to a current B) that a magnetic field varying with time gives rise to an electric field C) that a magnetic field varying with space gives rise to an electric field D) that energy density due to an electric field is $$\frac{1}{2}\varepsilon {{\text{E}}^2}$$

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Answer & Solution

Answer: Option A

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29

Consider the following statement about a transmission line having non-zero Parameters R, L, G and C:
1. By proper choice of the parameters, the line can be made lossless even though R and G are non-zero
2. The line will have both amplitude and phase distortion in general
Of the statements

A) 1 alone is true B) 2 alone is true C) Both 1 and 2 are true D) Both 1 and 2 are false

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Answer & Solution

Answer: Option B

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30

With wavelength λ in increasing order, which one of the following combination is correct?

A) EHF, SHF, UHF, VHF B) SHF, UHF, VHF, EHF C) UHF, VHF, EHF, SHF D) VHF, EHF, SHF, UHF

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Answer & Solution

Answer: Option A

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Electromagnetic Field Theory MCQ Questions & Answers | ECE