78. Which of the following frequency is likely to be a3sociated with AM radio broadcast?
A. 1000 kHz
B.100 MHz
C. 500 MHz
D. 10 GHz

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79. When El, E2, E3 etc. are the simultaneous modulating voltages, then the total modulating voltage Et will be
A.Et= El+ E2 + E3 +
B. Et= E12 + E22 E32
C. Et = 'E E32
D.E1 + E2 + E3 +

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80. A transmitter radiates 9 kW with the carrier unmodulated and 10.125 kW when the carrier is sinusoidally modulated. The modulation index will be
A.40%
B.44%
C.50%
D.66%

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81. If another sine wave, corresponding to 40% modulation, is transmitted simultaneously, determine the total radiated power
A. 9.9 kW
B. 10 kW
C. 10.42 kW
D. 10.84 kW

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82. When a broadcast AM transmitter is 50% modulated, its antenna current is 12 A. What will be the current when the modulation depth is increased to 90%?
A. 12.9A
B. 13.4 A
C. 16.6 A
D.21.8A

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83. In amplitude modulation, the carrier and the modulating voltages are given by e = E sin co c c mt em = Em sin comt.The modulation index will beE 1E2 + E2E3+ E3E4+(d) Et ? (a) One of the waves is not pure sine wave
A.(b) The modulation index is 0.5
B. The modulation index is 1.0
C. The output wave is distorted
D.

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84. The ratio of the total power in amplitude modulated wave to the unmodulated carrier power is given by
A.(a)= 1--
B. = = - -Pt Pc2Pc2m2-P,
C. =1+ - = -1471712Pc2Pc
D.

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