50.  In relation to TV receiver equipment, 'rabbit ears' refers to
A. shape of TV receiver cabinet
B. shape of test pattern displayed on the screen
C. picture distortion
D. receiving antenna

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51. Tropospheric scatter is used with frequencies in the following range :
A. H.F.
B. V.H.F.
C. U.H.F.
D. U.F.

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52. In a broadcast superheterodyne receiver, the
A. local oscillator operates below the signal frequency
B. mixer input must be tuned to the signal frequency
C. local oscillator frequency is normally double the IF
D. RFamplifier normally works at 455 kHz about the carrier frequency

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53.  For an electromagnetic wave travelling in free space, the power carried by the wave changes with distance `d' in proportion to
A. d
B.d1
C. ?d2
D. d2

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54. The radio circuit that works by changing the incoming radio frequency into another lower frequency is called a
A. tuned-radio-frequency receiver
B. regenerative circuit
C. superheterodyne receiver
D. IF receiver

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55. In commericial FM broadcasting, the maximum frequency deviation is normally ? kHz.
A.5
B.15
C.75
D.200

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56. When the modulating frequency is doubled, the modulation index is halved and the modulating voltage remains constant. The modulation system is
A. amplitude modulation
B. phase modulation
C. frequency modulation
D. any one of the three

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