Electromagnetic Field Theory MCQ Questions & Answers

31

In a charge-free space, the Poisson's equation results in which of the following?

A) Continuity equation B) Maxwell's equation C) Laplace equation D) None of the above

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Answer & Solution

Answer: Option C

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32

A TEM wave is incident normally upon a perfect conductor. The E and H fields at the boundary will be, respectively,

A) minimum and minimum B) maximum and maximum C) minimum and maximum D) maximum and minimum

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Answer & Solution

Answer: Option C

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33

Two identical copper wires W₁ and W₂ placed in parallel as shown in the figure, carry currents I and 2I, respectively, in opposite directions. If the two wires are separated by a distance of 4r, then the magnitude of the magnetic field \[\overrightarrow B \] between the wires at a distance r from W₁ is
Electromagnetic Field Theory mcq question image

Electromagnetic Field Theory mcq question image

A) \[\frac{{\mu _0^2{I^2}}}{{2\pi {r^2}}}\] B) \[\frac{{6{\mu _0}I}}{{5\pi r}}\] C) \[\frac{{{\mu _0}I}}{{6\pi r}}\] D) \[\frac{{5{\mu _0}I}}{{6\pi r}}\]

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Answer & Solution

Answer: Option D

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34

When a dielectric is placed in an electric field, the electric flux density D, electric field intensity E and polarization P are related as

A) $$\overline {\text{D}} = {\varepsilon _0}\overline {\text{E}} \times {\text{P}}$$ B) $$\overline {\text{D}} = {\varepsilon _0}\overline {\text{E}} - {\text{P}}$$ C) $$\overline {\text{D}} = {\varepsilon _0}\left( {\overline {\text{E}} \times {\text{P}}} \right)$$ D) $$\overline {\text{D}} = {\varepsilon _0}\overline {\text{E}} + {\text{P}}$$

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Answer & Solution

Answer: Option D

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35

Gilbert is a unit of

A) electromotive force B) magneto motive force C) conductance D) permittivity

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Answer & Solution

Answer: Option B

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36

If $${\vec a}$$ is a constant vector and $$\vec r = x\hat i + y\hat j + z\hat k,$$ then div $$\left( {\vec a \times \vec r} \right)$$ and curl $$\left( {\vec a \times \vec r} \right)$$ are given by

A) $$\left( {2\vec a,\,0} \right)$$ B) $$\left( {\vec a,\,0} \right)$$ C) $$\left( {0,\,2\vec a} \right)$$ D) $$\left( {0,\,\vec a} \right)$$

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Answer & Solution

Answer: Option C

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37

A material is described by the following electrical parameters at a frequency of 10 GHz σ = 10⁶ mho/m, µ = µ₀ and ∈/∈₀ = 10. The martial at this frequency is considered to be
$$\left( {{ \in _0} = \frac{1}{{36\pi }} \times {{10}^{ - 9}}{\text{F/m}}} \right)$$

A) a good conductor B) a good dielectric C) neither a good conductor, nor a good dielectric D) a good magnetic material

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Answer & Solution

Answer: Option A

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38

For a perfect matched load the value of standing wave ratio and reflection coefficient respectively are

A) 1, 0 B) 0, 0 C) 0, 1 D) ∞, 1

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Answer & Solution

Answer: Option A

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39

Laplace equation in cylindrical coordinates is given by:

A) \[{\nabla ^2}V = \frac{1}{\rho }\frac{\partial }{{\partial \rho }}\left( {\frac{{\rho \partial V}}{{\partial \rho }}} \right) + \frac{1}{{{\rho ^2}}}\left( {\frac{{{\partial ^2}V}}{{\partial {\phi ^2}}}} \right) + \frac{{{\partial ^2}V}}{{\partial {z^2}}} = 0\] B) \[{\nabla ^2}V = \frac{{{\partial ^2}V}}{{\partial {x^2}}} + \frac{{{\partial ^2}V}}{{\partial {y^2}}} + \frac{{{\partial ^2}V}}{{\partial {z^2}}}\] C) \[{\nabla ^2}V = - \frac{\rho }{\varepsilon }\] D) \[{\nabla ^2}V = \frac{1}{r}\frac{\partial }{{\partial r}}\left( {\frac{{{r^2}\partial V}}{{\partial r}}} \right) + \frac{1}{{{r^2}\sin \theta }}\frac{\partial }{{\partial \theta }}\left( {\sin \theta \frac{{\partial V}}{{\partial \theta }}} \right) + \frac{1}{{{r^2}{{\sin }^2}\theta }}\frac{{{\partial ^2}V}}{{\partial {\phi ^2}}} = 0\]

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Answer & Solution

Answer: Option A

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40

A measure of the mismatch between the maximum and minimum voltage and current variation along the transmission line is called SWR, i.e. standing wave ratio. SWR indicates how much power is delivered to the load, and how much is lost in the line. When SWR is 1, the percent reflected power is zero. When SWR is 1.5, the percent reflected power will be

A) 4 B) 8 C) 25 D) 40

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Answer & Solution

Answer: Option A

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Electromagnetic Field Theory MCQ Questions & Answers | ECE