JEE Questions for Physics Communication System Quiz 9 - MCQExams.com

Assertion A portable AM radio set must be kept horizontal to receive the signals properly.
Reason Radio waves are polarised electromagnetic waves.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Optical fibre communication has immunity to cross-talk.
Reason Optical interference between fibres is zero.
  • If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
Assertion Transmission Electron Microscope (TEM) provides two dimensional images.
Reason Scanning Electron Microscope (SEM) provides three dimensional images.
  • a) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion.
  • b) If both Assertion and Reason are true but Reason is not the correct explanation of the Assertion.
  • If Assertion is true but Reason is false.
  • If the Assertion and Reason both are false.
  • If Assertion is false but Reason is true.
A ground receiver station is receiving a signal at 5 MHz and transmitted from a ground transmitted at a height of 300 m, located at a distance of 100 km from the receiver station. The signal is coming via. (Radius of earth = 6.4 x 106m. Nmax of isosphere = 1012m3)
  • Space wave
  • Sky wave propagation
  • Satellite transponder
  • All of these
In the given detector circuit, the suitable value of carrier frequency is
Physics-Communication System-64289.png
  • << 109 Hz
  • << 105 Hz
  • >> 109 Hz
  • None of these

Physics-Communication System-64291.png

  • Physics-Communication System-64292.png
  • 100 Ω

  • Physics-Communication System-64293.png

  • Physics-Communication System-64294.png
A wave is represented as e = l0sin(108 t + 6sin 1250t) then the modulating index is
  • 10
  • 1250
  • 108
  • 6
An optical fibre communication system works on a wavelength of 1.3 µm. The number of subscribers it can feed if a channel requires 20 kHz are

  • Physics-Communication System-64296.png
  • 2)
    Physics-Communication System-64297.png

  • Physics-Communication System-64298.png
  • None of these
A telephone link operating at a central frequency of 10 GHz is established. If 1% of this is available then how many telephone channel can be simultaneously given when each telephone covering a band width of 5 kHz

  • Physics-Communication System-64300.png
  • 2)
    Physics-Communication System-64301.png

  • Physics-Communication System-64302.png

  • Physics-Communication System-64303.png
In a radio receiver, but short wave and medium wave stations are tuned by using the same capacitor but coils of different inductance Ls and Lm respectively then
  • Ls > Lm
  • Ls < Lm
  • Ls = Lm
  • None of these

Physics-Communication System-64306.png
  • 2 : 4 : 3
  • 4 : 3 : 2
  • 2 : 3 : 4
  • 3 : 2 : 4
A carrier is simultaneously modulated by two sine waves with modulation indices of 0.4 and 0.3. The resultant modulation index will be
  • 1.0
  • 0.7
  • 0.5
  • 0.35
Mean optical power launched into an 8 km fibre is 120µW and mean output power is 4µW, then the overall attenuation is (Given log 30 = 1.477)
  • 14.77 dB
  • 16.77 dB
  • 3.01 dB
  • None of these
An antenna current of an AM broadcast transmitter modulated by 50% is 11 A. The carrier current is
  • 10.35 A
  • 9.25 A
  • 10 A
  • 5.5 A
Because of tilting which waves finally disappear
  • Surface waves
  • Sky waves
  • Microwaves
  • Space waves
A study of binary stars is most helpful in
  • Finding their distances
  • Finding their temperature
  • Finding their masses
  • Verifying Newton's force law of gravitation
A group of bright and faint stars is called
  • Galaxy
  • Comet
  • Black hole
  • Constellation
According to modern astronomers into how many constellations, the whole sky is divided
  • 1011
  • 88
  • 880
  • 5000
Which of the following theories is the most satisfactory about the origin of the universe?
  • Big Bang theory
  • Pulsating theory
  • Steady state theory
  • None of the above
Which of the planet is brightest?
  • Mercury
  • Venus
  • Mars
  • Jupiter
A star which appears blue will be
  • As hot as the sun
  • Cooler than the sun
  • Very cold indeed
  • Much hotter than the sun
Hubble showed that the universe as a whole is expanding and the distant stars are receding from us. The spectral line from a star, when compared with the corresponding line from a source will then show
  • A shift in frequency towards the red end
  • A shift in frequency towards the violet end
  • No shift in frequency at all
  • A shift in frequency towards the violet end as well as a decrease in intensity
The solar constant on the surface of the earth is S. What will be it value on the surface of another planet which is about 5.3 A.U. away from sun?

  • Physics-Communication System-64311.png
  • 2)
    Physics-Communication System-64312.png

  • Physics-Communication System-64313.png

  • Physics-Communication System-64314.png
CO2 gas is found in which of the following pairs of the planet?
  • Earth and Mercury
  • Mercury and Saturn
  • Venus and Saturn
  • Venus and Mars
The wavelength of maximum energy, released during an atomic explosion, was 2.93×10–10 m. Given that the Wien\'s constant is 2.93 × 10–3 m K, the maximum temperature attained must be of the order of
  • 10–7 K
  • 107 K
  • 10–13 K
  • 5.86 × 10–7 K
Black hole is a
  • Hole in the ozone layer of atmosphere
  • Hole in earth's centre
  • Highly dense matter available in the atmosphere
  • Hole in troposphere
A planet of mass M has a satellite of mass m, revolving around the planet in a circular orbit of radius r and time period T. The mass (M) of the planet is

  • Physics-Communication System-64318.png
  • 2)
    Physics-Communication System-64319.png

  • Physics-Communication System-64320.png

  • Physics-Communication System-64321.png
The age of universe is believed to be
  • 1 billion years
  • 10 billion years
  • 10-20 billion years
  • 1000 billion years
Sun radiates continuously and maintains its brightness because
  • Helium is converted into iron in its core
  • Of fusion of hydrogen nuclei into helium
  • Fusion of helium in hydrogen
  • Burning of carbon, in its core
Venus appears brighter than other stars because
  • It is heavier than other planets
  • Its density is more than other planets
  • It is nearer to earth in comparison to other planets
  • Nuclear fusion takes place at its surface
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