JEE Physics Communication System MCQs Set A

Question: A device which provides output in electrical form or it has input in electrical form is called a

• a) Transducer
• b) Receiver
• c) Repeater
• d) Transmitter

Answer: Transducer

Question: Out of the following, which is not an essential element of a communication system?

• a) Transducer
• b) Receiver
• c) Communication channel
• d) Transmitter

Answer: Transducer

Question: Decrease in signal strength due to energy losses is called

• a) Attenuation
• b) Noise
• c) Interference
• d) Distortion

Answer: Attenuation

Question: The disturbance or distortion in the transmission and processing of message signals is called

• a) Noise
• b) Attenuation
• c) Interference
• d) None of these

Answer: Noise

Question: A repeater is a combination of

• a) All of these
• b) Transmitter
• c) AmplifierReceiver
• d) Receiver

Answer: All of these

Question: The frequency band of FM broadcast is

• a) 88 MHz to 108 MHz
• b) 88 Hz to 88 kHz
• c) None of these
• d) 800 kHz to 8000 MHz

Answer: 88 MHz to 108 MHz

Question:

• a)

  

• b)

  

• c)

  

• d)

  

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Question: Modulation is necessary

• a) All of these
• b) To avoid mixing up of signals from different transmitters
• c) To increase effective power radiated by antenna
• d) To select suitable size of antenna

Answer: All of these

Question: A device that connects one computer to another across ordinary telephone lines is called

• a) Modem
• b) None of these
• c) Fax
• d) Transducer

Answer: Modem

Question: Three waves A, B and C of frequencies 1600 kHz, 5 MHz and 60 MHz, respectively are to be transmitted from one place to another. Which of the following is the most appropriate mode of communication?

• a) A is transmitted via ground wave, B via sky wave and C via space wave
• b) A is transmitted via space wave while B and C are transmitted via sky wave
• c) B and C are transmitted via ground wave while A is transmitted via sky wave
• d) B is transmitted via ground wave while A and C are transmitted via space wave

Answer: A is transmitted via ground wave, B via sky wave and C via space wave

Question: A speech signal of 3 kHz used to modulate a carrier signal of frequency 1 MHz, using amplitude modulation. The frequencies of the side bands will be

• a) 1.003 MHz and 0.997 MHz
• b) 3001 kHz and 2997 kHz
• c) 1 MHz and 0.997 MHz
• d) 1003 kHz and 1000 kHz

Answer: 1.003 MHz and 0.997 MHz

More Questions..............................

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: An ‘antenna’ is

• a) Inductive
• b) Capacitative
• c) Resistive above its resonance frequency
• d) None of these

Answer: Inductive

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A male voice after modulation-transmission sounds like that of a female to the receiver. The problem is due to

• a) Poor bandwidth selection of amplifiers
• b) Poor selection of carrier frequency
• c) Loss of energy in transmission
• d) Poor selection of modulation index

Answer: Poor bandwidth selection of amplifiers

Question:  A basic communication system consists of

A. Transmitter B. Information source C. User of information D. Channel E. Receiver

Choose the correct sequence in which these are arranged in a basic communication system

• a) BADEC
• b) BDACE
• c) BEADC
• d) ABCDE

Answer: BADEC

Question: Identify the mathematical expression for amplitude modulated wave

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The distance between consecutive maxima and minima is given by

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: Long distance short-wave radio broad-casting uses

• a) Ionospheric wave
• b) Direct wave
• c) Ground wave
• d) Sky wave

Answer: Ionospheric wave

Question: The band width of amplitude modulation is

• a) Double the frequency of audio signal
• b) Double the frequency of carrier wave
• c) Equal to frequency of aduio signal
• d) Half the frequency of carrier wave

Answer: Double the frequency of audio signal

Question: Broadcasting antennas are generally

• a) Vertical type
• b) Omnidirectional type
• c) Horizontal type
• d) None of these

Answer: Vertical type

Question: For television broadcasting, the frequency employed is normally

• a) 30 - 300 MHz
• b) 30 - 300 GHz
• c) 30 - 300 kHz
• d) 30 - 300 Hz

Answer: 30 - 300 MHz

Question: The sound waves after being converted into electrical waves are not transmitted as such because

• a) They are highly absorbed by the atmosphere
• b) The frequency is not constant
• c) They travel with the speed of sound
• d) The height of antenna has to be increased several times

Answer: They are highly absorbed by the atmosphere

Question: The process of superimposing signal frequency (i.e., audio wave) on the carrier wave is known as

• a) Modulation
• b) Detection
• c) Reception
• d) Transmission

Answer: Modulation

Question: In an amplitude modulated wave for audio -frequency of 500 cycles/second, the appropriate carrier frequency will be

• a) 50,000 cycles/s
• b) 500 cycles/s
• c) 100 cycles/s
• d) 50 cycles/s

Answer: 50,000 cycles/s

Question: If there were no atmosphere, the average temperature on the surface of earth would be

• a) Lower
• b) Higher
• c) Same as now
• d) 0°C

Answer: Lower

Question:

• a) 55 km
• b) 50 km
• c) 60 km
• d) 100 km

Answer: 55 km

Question: Radio wave of constant amplitude can be generated with

• a) Oscillator
• b) Rectifier
• c) FET
• d) Filter

Answer: Oscillator

Question: Ozone layer above earth’s atmosphere will not

• a) Reflect back radiowaves
• b) Prevent ultraviolet rays from sun
• c) Prevent ultraviolet rays from sun
• d) Prevent infrared radiations from sun reaching earth

Answer: Reflect back radiowaves

Question: An audio signal of 0.1 V is used in amplitude modulation of a career wave of amplitude 0.3. The modulation index is

• a)

  

• b) 3
• c) 0.03
• d) None of these

Answer:

Question: The frequency of amplitude modulated wave is equal to

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The radio waves of frequency ranging from 2 MHz to 30 MHz are called

• a) Sky waves
• b) Ground waves
• c) Space waves
• d) None of these

Answer: Sky waves

Question: A device which connects one computer to another is known as

• a) Modem
• b) FAX
• c) Laser lazer
• d) Photostat machine

Answer:  Modem

Question: Loss of strength of a signal is known as

• a) Attenuation
• b) Modulation
• c) De-modulation
• d) Noise

Answer: Attenuation

Question: Which of the following is an advantage of FM over AM?

• a) Less noise
• b) Larger bandwidth
• c) Can be transmitted to longer distance
• d) More circuit complexity

Answer: Less noise

Question: The process of changing some characteristic of a carrier wave in accordance with the signal to be transmitted is called

• a) Modulation
• b) None of these
• c) Rectification
• d) Amplification

Answer: Modulation

Question: Modulation is done in

• a) Transmitter
• b) Radio receiver
• c) None of these
• d) Communication channel

Answer: Transmitter

Question: “Need for modulation” arises due to which of the following reasons?

• a) All of these
• b) It allows multiple user-friendly communication
• c)

  

• d)

  

Answer: All of these

Question: A ground receiver station is receiving a signal at 500 MHz transmitted from a ground transmitter at a height of 300 m located at a distance of 500 km. It is coming via

• a) Satellite communication
• b) Sky wave
• c) Space wave
• d) Ground wave

Answer: Satellite communication

Question:

• a)

  

• b)

  

• c)

  

• d)

  

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