Physics - Principles of Communication

Question - 1

The distance between consecutive minima on a trasmission line is given by

  • A \(\lambda \)
  • B \(\frac { \lambda }{ 2 } \)
  • C \(\frac { \lambda }{ 4 } \)
  • D \(\frac { \lambda }{ 8 } \)

Question - 2

Repeaters are required every 40-50 km in a microwave terrestrial communication system because

  • A the curvature of the earh limits the distance over which lin-of-sight can be established
  • B microwave power decreases rapidly with distance
  • C signal-to-noise ratio decreases rapidly with distance
  • D signal distrortion creeps in rapidly with distance.

Question - 3

A modulator 

  • A generates constant frequency radiowaves
  • B generates variable frequency radiowaves
  • C improves signal-to-noise ratio
  • D improves thermal stablity

Question - 4

In an AM waveform, the amplitude of side band is

  • A independent of modulation index
  • B independent of carrior amplitude
  • C dependent on the amplitude of carrier wave only
  • D dependent on the amplitude of carrier

Question - 5

A short circuited, uniform, lossless transmission line of 0.04 wavelength long, acts almost like an ideal

  • A capacitor
  • B inductor
  • C series resonant circuit
  • D parallel resonant circuit

Question - 6

The standard broadcast FM signal occupies a band width of about

  • A 15 kHz
  • B 53 kHz
  • C 75 kHz
  • D 200 kHz

Question - 7

A commonly used in-band signalling frequency is

  • A 400 Hz
  • B 1000 Hz
  • C 2400 Hz
  • D 3825 Hz

Question - 8

In AM, total modulation index must not exceed unity or else

  • A the system will fail
  • B distortion will result
  • C amplifier wil be damaged
  • D resonant waves will be generated

Question - 9

In a frequency modulation system the number of important sidebands depends on

  • A the deviation alone
  • B the modulation frequency alone
  • C the modulation index alone
  • D the modulating frequency and the modulation index

Question - 10

Which of the following systems is NOT analog?

  • A Pressure gauge
  • B Clinical thermometer
  • C Trasistor radio receiver
  • D Ordinary electric switch
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