+2 Physics Unit 10 - Communication Systems

8 Questions | Total Attempts: 1897

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+2 Physics Unit 10 - Communication Systems

Prepared by P. ILAIYARAJA M. Sc. ,B. Ed. , PG ASST IN PHYSICS , GHSS, PANCHANATHIKKULAM EAST, NAGAI DT.   ; & www. Padasalai. Net


Questions and Answers
  • 1. 
    High frequency waves follow
    • A. 

      Ionospheric propagation

    • B. 

      The curvature of the earth

    • C. 

      The ground wave propagation

    • D. 

      The line of sight direction

  • 2. 
    The main purpose of modulation is to
    • A. 

      transmit low frequency information over long distances efficiently

    • B. 

      Produce side bands

    • C. 

      Acquire wave shaping of the carrier wave

    • D. 

      Combine two waves of different frequencies

  • 3. 
    In amplitude modulation
    • A. 

      The amplitude of the carrier wave varies in accordance with the amplitude of the modulating signal.

    • B. 

      The amplitude of the carrier wave remains constant

    • C. 

      The amplitude of the carrier varies in accordance with the frequency of the modulating signal

    • D. 

      Modulating frequency lies in the audio range

  • 4. 
    In amplitude modulation, the band width is
    • A. 

      Twice the signal frequency

    • B. 

      Thrice the signal frequency

    • C. 

      Four times the signal frequency

    • D. 

      Equal to the signal frequency

  • 5. 
    In phase modulation
    • A. 

      Both the phase and the frequency of the carrier wave varies.

    • B. 

      There is no change in the frequency and phase of the carrier wave

    • C. 

      Only the phase of the carrier wave varies

    • D. 

      Only the frequency of the carrier wave varies.

  • 6. 
    The RF channel in a radio transmitter produces
    • A. 

      High frequency carrier waves

    • B. 

      both audio signal and high frequency carrier waves

    • C. 

      Low frequency carrier waves.

    • D. 

      Audio signals

  • 7. 
    The purpose of dividing each frame into two fields so as to transmit 50 views of the picture per second is
    • A. 

      To avoid flicker in the picture

    • B. 

      The fact that handling of higher frequencies is easier

    • C. 

      that 50 Hz is the power line frequency in India

    • D. 

      To avoid unwanted noises in the signals

  • 8. 
    Printed documents to be transmitted by fax are converted into electrical signals by the process of
    • A. 

      Scanning

    • B. 

      modulation

    • C. 

      Light variation

    • D. 

      Reflection

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