Electromagnetic Field Thoery - ECE Questions and Answers

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Laplacian of a scalar function v is

gradient of v

divergence of v

gradient of the gradient of v

divergence of the gradient of v

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The numerical value of directive gain may lie between

1 and + 1

0 and 1

0 and ∞

1 and ∞

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The wave propagation occurs without attenuation in case of a

conductor

semiconductor

perfect dielectric

none of the above

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A vertical wire of 1 meter length carries a current of 1 A at 10 MHz. The total radiated power is nearly

0.13 W

0.88W

7.3 W

73 W

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A plane EM wave is travelling in an unbound loss less dielectric having μ_y = 1 and ε_y = 4, the time average Poynting vector of the wave is 5 W/m³ . The phase velocity v_p (assuming velocity of light as 3 x 10⁸ m/sec) is

1.5 x 10⁸ m/sec

3 x 10⁸ m/sec

2.5 x 10⁸ m/sec

0.5 x 10⁸ m/sec

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The phase velocity in a coaxial line is

greater than C

equal to C

less than C

not depend on C

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D-layer extends approximately from

50 to 90 km

20 to 50 km

90 to 110 km

up to 50 km

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The ionosphere plays a significant role in radio wave propagation at

high frequency

ultra-high frequencies

microwave frequency

optical frequencies

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Radiation resistance for wire antenna is

55 Ω

65 Ω

100 Ω

377 Ω