Electromagnetic Field Theory MCQ Questions & Answers

61

Which of the following mechanisms is NOT for removing particulate matter from gas streams.

A) Gravitational settling B) Centrifugal impaction C) Electrostatic precipitation D) Burning the particulate

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Answer & Solution

Answer: Option D

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62

Polarization is characteristic of EM wave that gives the direction of

A) Electrical component of a wave with respect to ground B) Magnetic component of EM wave with respect to ground C) Both electrical and magnetic components with respect to ground D) None of the above

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Answer & Solution

Answer: Option A

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63

For a transmission of wave from a dielectric medium of permittivity ε₁ into a dielectric medium of lower permittivity ε₂ and (ε₁ > ε₂) the critical angle of incidence θ_c (relative to the interface) is given by

A) $${\sin ^{ - 1}}\sqrt {\frac{{{\varepsilon _2}}}{{{\varepsilon _1}}}} $$ B) $${\cos ^{ - 1}}\sqrt {\frac{{{\varepsilon _2}}}{{{\varepsilon _1}}}} $$ C) $${\tan ^{ - 1}}\sqrt {\frac{{{\varepsilon _2}}}{{{\varepsilon _1}}}} $$ D) $${\sin ^{ - 1}}\sqrt {\frac{{{\varepsilon _1}}}{{{\varepsilon _2}}}} $$

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Answer & Solution

Answer: Option A

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64

A parallel plate capacitor of 100 pF having an air dielectric is charged to 10 kV. It is then electrically isolated. The plates are pulled away from each other until the distance is ten times more than before. Estimate the energy needed to pull the plates.

A) 0.05 Joules B) 50 Joules C) 500 Joules D) -50 Joules

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Answer & Solution

Answer: Option A

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65

The intrinsic impedance of free space is 377 Ω. The approximate intrinsic impedance of a medium with relative permittivity and permeability of 4 and 1 respectively will be

A) 75 Ω B) 94 Ω C) 188 Ω D) 377 Ω

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Answer & Solution

Answer: Option C

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66

In a uniform plane wave 'E' and 'H' are related by

A) $$\frac{{\overrightarrow E }}{{\overrightarrow H }} = l$$ B) $$\frac{{\overrightarrow E }}{{\overrightarrow H }} = \frac{\varepsilon }{\mu }$$ C) $$\frac{{\overrightarrow E }}{{\overrightarrow H }} = \sqrt {\frac{\mu }{\varepsilon }} $$ D) $$\frac{{\overrightarrow E }}{{\overrightarrow H }} = \infty $$

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Answer & Solution

Answer: Option C

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67

In a coaxial transmission line (ε_r = 1), the electric field intensity is given by:
$$E = \frac{{100}}{\rho }\cos \left( {{{10}^9}t - 6z} \right){u_p}{\text{V/m}}$$
The displacement current density is

A) $$ - \frac{{100}}{\rho }\sin \left( {{{10}^9}t - 6z} \right){u_p}{\text{A/}}{{\text{m}}^2}$$ B) $$\frac{{116}}{\rho }\sin \left( {{{10}^9}t - 6z} \right){u_p}{\text{A/}}{{\text{m}}^2}$$ C) $$ - \frac{{0.9}}{\rho }\sin \left( {{{10}^9}t - 6z} \right){u_p}{\text{A/}}{{\text{m}}^2}$$ D) $$ - \frac{{216}}{\rho }\cos \left( {{{10}^9}t - 6z} \right){u_p}{\text{A/}}{{\text{m}}^2}$$

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Answer & Solution

Answer: Option C

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68

The torque (in N - m) acting on a circular current loop of radius 1 mm in the xy-plane, connected at the origin and with current 0.1 A flowing in the sense of increasing φ in a magnetic field $$B = {10^{ - 5}}\left( {2{{\hat a}_x} - 2{{\hat a}_y} + {{\hat a}_z}} \right){\text{Wb/}}{{\text{m}}^2}{\text{ is:}}$$

A) $$ - 2 \times {10^{ - 12}}\left( {2{{\hat a}_x} - 2{{\hat a}_y} + {{\hat a}_z}} \right)$$ B) $$2 \times {10^{ - 12}}\pi \left( {{{\hat a}_y} + {{\hat a}_x}} \right)$$ C) $${10^{ - 12}}\pi $$ D) $$ - {10^{ - 12}}\pi $$

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Answer & Solution

Answer: Option B

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69

When a line short circuited at far end, the minimum voltage occurs at

A) Far end B) Source end C) Midway between source and load D) None of these

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Answer & Solution

Answer: Option A

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70

A 3 µF capacitor is charged by a constant current of 2 µA for 6 seconds. The voltage across the capacitor to the end of charging will be:

A) 3 V B) 4 V C) 6 V D) 9 V

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Answer & Solution

Answer: Option B

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Electromagnetic Field Theory MCQ Questions & Answers | ECE