Q.1
The instrument/ equipment which transform one form of energy into another form of energy is called a _______
  • a)transponder
  • b) transducer
  • c)receiver
  • d)transmitter
Q.2
Which of the following are modulation techniques for digital communication?
  • a) ASK
  • b) FSK
  • c)PSK
  • d)All of them
Q.3
What is the main function of transponder
  • a) To amplify the signal
  • b) To change its frequency
  • c)Both (a) and (b)
  • d)none of them
Q.4
Electromagnetic waves used in medicine to destroy cancer cells
  • a) radio waves
  • b) infrared rays
  • c) gamma rays
  • d) ultraviolet rays
Q.5
In electromagnetic spectrum, the visible light lie between
  • a)radiowaves and microwaves
  • b) ultraviolet rays and infrared rays
  • c)ultraviolet rays and x rays
  • d)infrared rays and microwaves
Q.6
Which of the following statements is not true in case of electromagnetic waves?
  • a)they are light waves
  • b)they are transverse waves
  • c)propagates through space
  • d)they are longitudinal waves
Q.7
In an electromagnetic wave in free space, the direction of electric field vector E is along y axis and magnetic field vector B is along z axis then which of the following is true
  • a)(E × B) × E=1
  • b)(E × B) × B=1
  • c)(E × B) × B=0
  • d)none of these
Q.8
When a plane electromagnetic wave travels in vacuum, the average electric energydensity is given by (Eo is the amplitude of the electric field)
  • a)
    ch-20_qn-224choice_img_no1.png
  • b)
    ch-20_qn-224choice_img_no2.png
  • c)
    ch-20_qn-224choice_img_no3.png
  • d)
    ch-20_qn-224choice_img_no4.png
Q.9
In a plane electromagnetic wave , the electric field oscillates sinusoidaly at a frequency of 2.0×1010Hz. if the peak value of electric field is 60V/m the average energy density (in Jm-3) of the magnetic field of the wave will be
  • a)2π×10-7
  • b) 10-7 / 2π
  • c)4π×10-7
  • d) 10-7 / 4π
Q.10
If the earth were not having atmosphere, its temperature________.
  • a)would have been low
  • b)would have been high
  • c)would hav remain constant
  • d)none of these
Q.11
_________ is responsible for the green house effect
  • a) infrared rays
  • b) ultraviolet rays
  • c)x raya
  • d)radiowaves
Q.12
When an electromagnetic wave encounters a dielectric medium, the transmittedwave has
  • a) same frequency but different amplitude
  • b) same amplitude but different frequency
  • c) same frequency and amplitude
  • d) different frequency and amplitude
Q.13
An electromagnetic wave
  • a)can be deflected by electric field
  • b)can be deflected by magnetic field
  • c)can be deflected bye both electric and magnetic field
  • d)none of these
Q.14
The potential difference between the plates of a parallel plate capacitor is chargingat the rate of 106V/s . If the capacitance is 2µF . The displacement current inthe dielectric of the capacitor will be
  • a)4A
  • b)3A
  • c)2A
  • d)1A
Q.15
What should be the minimum length of the antenna capable of emitting audio signal ofwave length λ ?
  • a)λ/4
  • b) λ/8
  • c)λ/2
  • d)λ
Q.16
_________is used as a medium an space communication
  • a) Two wire line
  • b) Space
  • c) Amplifier
  • d) Optical fibre
Q.17
The band width of Audio signal is
  • a)20 HZ
  • b)20 KHZ
  • c)20 MHz
  • d)20 GHz
Q.18
ground waves are polarized at direction.
  • a)vertically upward
  • b)horizontal
  • c)tangential direction to the surface of the earth
  • d)in all four.
Q.19
Intensity of electric field of ground waves is in of the distance travelled by it.
  • a) Square
  • b) inverse of root
  • c)proportion
  • d)inverse
Q.20
In radio and television broadcast, the information signal is in the form of
  • a) analog signal
  • b) digital signal
  • c) Both analog and digit signals
  • d) neither analog nor digital signal
Q.21
In light modulation, which characteristic of the carrier light wave is varied?
  • a)Amplitude
  • b) Frequency
  • c)Phase
  • d)intensity
Q.22
Though which mode of communication can radiowaves be sent from one Plate toanother?
  • a)Ground wave ProPagation
  • b)sky wave Propagation
  • c)Space wave ProPagation
  • d)All of the above
Q.23
Which range of Frequencies is Suitable for sky wave Propagation ?
  • a) 1 KHz to 500 KHz
  • b) 1 MHz to 2 MHz
  • c)2 MHz to 20 MHz
  • d)Above 30 MHz
Q.24
Which of the Following is not a component of communication System ?
  • a) Transmitter
  • b) Transmission channel
  • c) Noise
  • d) Receiver
Q.25
Device which transform one form of energy in to another form of energy is called a
  • a)Transducer
  • b)Transformer
  • c)Transponder
  • d)Transistor
Q.26
----- is a link between the transmitter and receiver
  • a)Microphone
  • b)Transmission Channel
  • c)transducer
  • d)telephone
Q.27
______in the receiver section are used to reduce the level of noise signal
  • a) filter circuit
  • b) Modulator
  • c)de modulator
  • d)Amplifier
Q.28
The minimum distance a up to which T.V transmission from a T.V. tower of height h canbe received is Proportional to
  • a) h1/2
  • b) h
  • c) h3/2
  • d) h2
Q.29
For an amplitude modulated wave, the maximum amplitude is found to be 9V while theminimum amplitude is found to be 3V. The modulation index is
  • a)100%
  • b)75%
  • c)50%
  • d)25%
Q.30
AM is used for broadcasting because
  • a) it is more noise innumerable than other modulation system
  • b) it requires less transmitting power compared with other system
  • c)it's avoids receiver complexity....
  • d)No other modulation system can provide the necessary band width faithful transmission
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