Electromagnetic Field Thoery - ECE Questions and Answers

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The intrinsic impedance of free space

increases with increase of frequency

decreases with increase of frequency

is independent of frequency

none

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To couple a coaxial line to a parallel to wire line it is best to use a

slotted line

balun

directional coupler

quarter wave transformer

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The shunt admittance of a transmission line is given by

γ = R + jωL

γ = R - jωL

γ = G + jωC

γ = jωGC

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A dipole antenna was radiating with some excitation in free space radiating a certain amount of the power. If this antenna is immersed in a lake where water is non-dissipative but has a dielectric constant of 81, the radiated power with the same excitation will

decrease to finite non-zero value

remain the same

increase

decrease to zero

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If short-circuited and open circuited impedances are 5 ohms and 20 ohms, then characteristic impedance is

1 ohms

10 ohms

25 ohms

100 ohms

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Electric lines of force do not cross each other because

the lines of force mutually repel each other

the lines of force emanate from a point charge

the tangent to the line of force gives the direction of E and if they cross two tangents for E which is not possible

none of the above

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A person with a receiver is 5 km away from the transmitter. What is the distance that this person must move further to detect at 3 dB decrease in signal strength?

942 m

2070 m

4978 m

5320 m