Tag: elements of a communication system

Questions Related to elements of a communication system

The wave used by artificial satellites for communication is

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. Microwaves

  2. Infrared rays

  3. Radio rays

  4. X-rays

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Correct Option: A
Explanation:

Microwaves are mostly used for satellite communication, as microwaves can pass straight through the atmosphere and connect antennas on earth to satellite in earth's orbit.

The critical velocity of satellite of mass $100 kg$ moving round a planet is $20 m/s$. If another satellite of mass $200 kg$ is kept moving in the same orbit then its critical velocity will be:

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. $40 km/hr$

  2. $72 km/hr$

  3. $40 m/s$

  4. $72 m/s$

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Correct Option: B

In sky wave communication which of the frequency will be reflected back by the ionospheric layer having electron density $4 \times 10 ^ { 6 } / \mathrm { m } ^ { 3 }$

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. $19 \times 10 ^ { 3 } \mathrm { Hz }$

  2. $9 \times 10 ^ { 3 } H z$

  3. $31 \times 10 ^ { 3 } \mathrm { Hz }$

  4. $20 \times 10 ^ { 3 } \mathrm { Hz }$

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Correct Option: B

The examples of broadcast are
A) radio B) television
C) telephony D) internet

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. A & B

  2. A, B & D

  3. A,B & C

  4. B & D

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Correct Option: B
Explanation:

telephone is one to one, whereas internet can have have many ways of communication, but radio and television broadcast the messages.

A digital signal

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. is less reliable than analog signal

  2. is more reliable than analog signal

  3. is equally reliable as the analog signal

  4. Not at all reliable

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Correct Option: B
Explanation:

Noise is added to digital signal also but its easier to remove the noise and amplify the digital signals as compared to analog signals, because analog signals contain many frequencies.

Statement A: If the antenna is vertical,a vertically polarised EM wave is radiated
Statement B: The vertically polarised EM wave has electrical variations in the vertical plane

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. A is true but B is false

  2. A is false but B is true

  3. A and B are false

  4. A and B are true

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Correct Option: D
Explanation:

Polarization of wave depends upon the orientation of the antenna. direction of polarization is along the orientation of antenna. By convention, direction of polarization of an EM wave is along the variation of electric field.

An antenna serves the following purpose : 

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. Converts AF wave to RF wave

  2. Converts RF signal into electromagnetic energy

  3. Converts the guided EM waves into free space EM waves and vice versa

  4. Superimposes AF wave on RF wave

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Correct Option: C
Explanation:

The antenna serves as the region of transition between guided and free space propagation.

The concepts of communication are
a) mode of communication
b) need for modulation
c) types of modulation
d) detection of modulated wave

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. a, b, c are true

  2. b, c, d are true

  3. c, d, a are true

  4. a, b, c & d are true

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Correct Option: D
Explanation:

In the concept of communication,

(a) Modes of communication are video, audio, face-to-face and text transmission.
(b) Modulation is needed, because original signal doesn't have the power to reach the desired destination, so it is modulated.
(c) Modulation are of different types, as amplitude modulation, frequency modulation and phase modulation etc. 
(d) Detection of modulated wave is done to extract the original signal from modulated wave.

Buffer amplifier is used at the transmitting end to

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. feed carrier frequency to master oscillator

  2. amplify carrier frequency

  3. mix modulating signal with carrier frequency

  4. isolate master oscillator from other stages of transmitter.

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Correct Option: D
Explanation:

Displacement current is set up in a region where the electric field is changing with time.

The science of communication involving long distances is known as

physics communication system elements of a communication system elements of communication system electromagnetic waves and communication system

  1. mass-communication

  2. distant-communication

  3. tele-communication

  4. trans-communication

Show answer
Correct Option: C
Explanation:
Telecommunication is the transmission of signs, signals, messages, writings, images and sounds or intelligence of any nature by wire, radio, optical or other electromagnetic systems. Telecommunication occurs when the exchange of information between communication participants includes the use of technology. 
 It is transmitted either electrically over physical media, such as cables, or via electromagnetic radiations.
20th and 21st century technologies for long-distance communication usually involve electrical and electromagnetic technologies, such as telegraph, telephone, and  radio, fiber optics, and communication satellites.