JEE Questions for Physics Communication System Quiz 11 - MCQExams.com

Suppose a planet goes around Sun with a linear speed twice as fast that of earth. What will be it\'s orbit size as compared to that of earth? (Radius of earth = R)
  • R/4
  • R /2
  • R
  • 2R
Assertion The comet do not obey Kepler\'s laws of planetary motion.
Reason The comet do not have elliptical orbit.
  • 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 A star which appears blue will be much hotter than the sun.
Reason It is based on Wein\'s law.
  • 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 Red shift confirms that the universe is expanding.
Reason Wavelength of red light is maximum in the visible region.
  • 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 Sun is at the galactic centre C of the milky way.
Reason All planets of solar system revolve around the sun.
  • 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 Moon is seen as it partly reflects the sun light falling on it.
Reason Moon is a satellite of earth. It does not emit light of its own.
  • 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 The value of Hubble\'s constant is 16 km/s
Reason Hubble\'s constant means that a galaxy at 1 million light years away is receding at the rate of 16 km/s
  • 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.
\ The universe is expanding\ means
  • Size of the hole in Ozone layer is increasing
  • Universe is expanding into something
  • Infinite universe is becoming more infinite
  • None of the above
Suppose the sun was located at the position occupied by the nearest star, say, alphacenturi 4 light years away. By what factor the solar radiation received per sec per unit area decrease
  • 1.5 × 10–6
  • 1.5 × 10–8
  • 1.5 × 10–9
  • 1.5 ×10–11
If a galaxy is at a distance 430 million light years from us, determine Hubble\'s constant. Its speed being 6.48 × 106 ms–1
  • 16 kms–1 per million light year
  • 15 kms–1 per million light year
  • 14 kms–1 per million light year
  • None of the above

Physics-Communication System-64349.png
  • 7.5
  • 102
  • 103
  • 107.5
A body at 1500 K° emits maximum energy at a wavelength 20,000 Å. If the Sun emits maximum energy at wavelength 5500 Å, then the temperature of Sun is
  • 5454
  • 4454
  • 4550
  • 5400
The hottest type of stars are called
  • A type
  • B type
  • O type
  • M type
If angular diameter of Sun is about 30’ and it\'s distance from earth is 1.5 × 1011 m, then solar diameter is
  • 1.1 × 107 m
  • 1.5 × 108 m
  • 1.4 × 109 m
  • 1.9 × 1011 m
The death of a star results is a neutron star if the original mass of star in terms of mass of Sun (M) is
  • Less than 2M
  • Between 2M and 4M
  • Greater than 5 M
  • Exactly equal to M
The tail of a comet points
  • Towards the Sun
  • Away from the Sun
  • In arbitrary
  • Away from the earth
The number of stars in our solar system is
  • 9
  • 5
  • 1
  • More than 9
In short wave communication, waves of which of the following frequencies will be reflected back by the Ionospheric layer, having electron density 1011 per m3
  • 2 MHz
  • 10 MHz
  • 12 MHz
  • 18 MHz
The process of superimposing signal frequency (i. e., audio wave) on the carrier wave is known as
  • Transmission
  • Reception
  • Modulation
  • Detection
Long distance short-wave radio broadcasting uses
  • Ground wave
  • Ionospheric wave
  • Direct wave
  • Sky wave
The characteristics impedance of a coaxial cable of the order of
  • 50 Ω
  • 200 Ω
  • 27 Ω
  • None of these
In which frequency range, space waves are normally propagated
  • HF
  • VHF
  • UHF
  • SHF
Through which mode of propagation, the radio waves can be sent from one place to another
  • Ground wave propagation
  • Sky wave propagation
  • Space wave propagation
  • All of the above
A laser beam of pulse power 1012 watt is focused on an object of area 10–4 cm2. The energy flux in watt/cm2at the point of focus is
  • 1020
  • 1016
  • 108
  • 104
The carrier frequency generated by a tank circuit containing 1nF capacitor and 10 µH inductor is
  • 1592 Hz
  • 1592 MHz
  • 1592 kHz
  • 159.2 Hz
Broadcasting antennas are generally
  • Omnidirectional type
  • Vertical type
  • Horizontal type
  • None of these
Maximum usable frequency (MUF) in F-region layer is x, when the critical frequency is 60 MHz and the angleof incidence is 70°. Then x is
  • 150 MHz
  • 170 MHz
  • 175 MHz
  • 190 MHz
The electromagnetic waves of frequency 2 MHz to 30 MHz are used
  • In ground wave propagation
  • in sky wave propagation
  • in microwave propagation
  • In satellite communication
A laser is a coherent source because it contains
  • Many wavelengths
  • Uncoordinated wave of a particular wavelength
  • Co-ordinated wave of many wavelengths
  • Co-ordinated waves of a particular wavelength
The attenuation in optical fibre is mainly due to
  • Absorption
  • Scattering
  • Neither absorption nor scattering
  • Both (a) and (b)
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