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Bihar Board Class 12 (Science) Communication Systems — practice questions — page 2

Explore 65 free Communication Systems questions in Bihar Board Class 12 (Science) Physics. Open each question or exercise to read its content, reference answers and available explanation.

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Communication Systems questions and exercises with answers

Showing questions 31–60 of 65.

Which device lets a computer send bits over a telephone line as tones?Read the answer and worked solution →Which was the earliest modulation method used for audio in radio broadcasting?Read the answer and worked solution →Radiotelephone experiments that led to AM began in which year?Read the answer and worked solution →Standard AM is called double-sideband because its sidebands lieRead the answer and worked solution →The RF bandwidth of an AM transmission is what multiple of the baseband bandwidth?Read the answer and worked solution →Which AM form needs half the bandwidth of standard AM?Read the answer and worked solution →In full sine-wave AM, carrier power relative to sideband power isRead the answer and worked solution →Why does suppressing the AM carrier improve efficiency?Read the answer and worked solution →The AM modulation index compares modulation excursions to what level?Read the answer and worked solution →The simplest AM demodulator uses a diode as aRead the answer and worked solution →Who developed a diode radio-wave detector in 1904?Read the answer and worked solution →Who invented wideband FM radio?Read the answer and worked solution →Compared with AM, FM offers improved what?Read the answer and worked solution →Wideband FM needs what compared with AM for an equal message?Read the answer and worked solution →FM broadcasting for high fidelity commonly uses which band?Read the answer and worked solution →How is sound carried in analog television broadcasts?Read the answer and worked solution →Which FM type saves bandwidth in two-way mobile voice radio?Read the answer and worked solution →FM at audio frequencies is used for what purpose?Read the answer and worked solution →Carson's rule gives a rule of thumb for which FM quantity?Read the answer and worked solution →Frequency deviation in FM is the difference between carrier frequency and itsRead the answer and worked solution →Which two methods are complementary forms of angle modulation?Read the answer and worked solution →In analog VCRs such as VHS, which video component is recorded using FM?Read the answer and worked solution →Some bats lower their echolocation frequency to offset which effect?Read the answer and worked solution →How is a stereo signal carried on a wideband FM signal?Read the answer and worked solution →Skywave propagation relies on reflection from which atmospheric layer?Read the answer and worked solution →The ionosphere begins at about what altitude?Read the answer and worked solution →Most long-distance shortwave skywave communication lies in which range?Read the answer and worked solution →Why can skywaves reach beyond the horizon?Read the answer and worked solution →What mainly causes fading of skywave signals?Read the answer and worked solution →Signals above about 30 MHz mostly do what to the ionosphere?Read the answer and worked solution →

Worked practice questions

Which device lets a computer send bits over a telephone line as tones?

  1. Antenna
  2. Speaker
  3. Modem
  4. Repeater
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Correct answer: C. Modem

A modem represents digital bits as audible tones so that an ordinary telephone line can carry them.

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Which was the earliest modulation method used for audio in radio broadcasting?

  1. AM
  2. FSK
  3. PM
  4. FM
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Correct answer: A. AM

Amplitude modulation was developed first, in the early twentieth century, for sending audio by radio.

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Radiotelephone experiments that led to AM began in which year?

  1. 1900
  2. 1865
  3. 1975
  4. 1945
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Correct answer: A. 1900

Fessenden and de Moura carried out radiotelephone experiments in 1900, the start of amplitude modulation for audio.

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