UPSC_Exams > UPSC_Indian_Engineering_Services_Answer > UPSC_IES_EC_2014_Answer_Key_Question_par
ENGINEERING > ELECTRONICS
1) The electric field in an electromagnetic wave (in vacuum) is described by
E = Emaxsin(Kx-?t)
where Emax = 100 N/C and K = 1 x 10 7 m-1
Speed of light is 3x10 8 m/s. What is the amplitude of the corresponding magnetic wave?
A) 4.57x10-7TB) 2.99 x 10-7 T
C) 3.33x107TD) 2.99 x 107 T
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Answer : 3.33x107T


ENGINEERING > ELECTRONICS
2) For transverse electric waves between parallel plates, the lowest value of m, without making all the field components zero, is equal to
A) 3B) 2
C) 1D) 0
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Answer : 1


ENGINEERING > ELECTRONICS
3) A 20 dB directional coupler is shown in the figure.
The power output at port will be
A) 10 mW
B) 1 mW
C) 5 mW
D) 2 mW
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Answer : 1 mW


ENGINEERING > ELECTRONICS
4) A loss-less transmission line of length l is open-circuited and has characteristic impedance Z0. The input impedance is
A) +jZ0 tan ?lB) -jZ0 tan ?l
C) -jZ0 cot ?lD) +jZ0 cot ?l
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Answer : -jZ0 cot ?l


ENGINEERING > ELECTRONICS
5) Conditions for a transmission line to be of low loss are
A) R ?L,G ?CB) R ?L,G ?C
C) R ?L,G ?CD) R ?L,G ?C
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Answer : R ?L,G ?C


ENGINEERING > ELECTRONICS
6) In a waveguide, attenuation near the cut-off frequency is
A) lowB) high
C) very highD) zero
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Answer : very high


ENGINEERING > ELECTRONICS
7) The phase velocity of waves propagating in a hollow metal waveguide is
A) equal to the group velocityB) equal to the velocity of light in free space
C) less than the velocity of light in free spaceD) greater than the velocity of light in free space
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Answer : greater than the velocity of light in free space


ENGINEERING > ELECTRONICS
8) Compensation theorem applicable to antennas is also called as
A) Millman's theoremB) superposition theorem
C) substitution theoremD) power transfer theorem
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Answer : substitution theorem


ENGINEERING > ELECTRONICS
9) An isotropic radiator is one which radiates energy
A) in a well-defined directionB) uniformly in all directions
C) inside a hollow spaceD) uniformly in horizontal plane
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Answer : uniformly in all directions


ENGINEERING > ELECTRONICS
10) The effective length of an antenna is a measure of
A) length of the antenna neglecting fringe effectsB) effectiveness of the antenna as a radiator/collector of electro magnetic energy
C) power consumed by the antennaD) range of the antenna
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Answer : effectiveness of the antenna as a radiator/collector of electro magnetic energy