Introducing the latest Class 12 Physics MCQs for Chapter 15, complete with answers. These MCQ questions are crafted in accordance with the latest exam pattern, helping students enhance their understanding of the chapter and achieve excellent marks in board exams.
MCQs On Communication System With Answers Pdf
Here are 30 multiple choice questions (MCQs) on communication systems, covering various concepts and topics essential for exams and competitive tests:
Q. As compared to sound waves, the frequency of radio waves is:
a) Lower
b) Higher
c) Equal
d) May be higher or lower
Answer: b
Q. Decrease in the strength of a signal is known as:
a) Tuning
b) Modulation
c) Attenuation
d) Amplification
Answer: c
Q. If the frequency of the modulated wave is less than the frequency of the carrier wave, then the input signal is:
a) Negative
b) Positive
c) Zero
d) Infinite
Answer: a
Q. At the end of the communication system, the signal is converted from radio to:
a) Sound
b) Mechanical energy
c) Kinetic energy
d) Potential energy
Answer: a
Also Read: Electric Charges and Fields
Q. Energy is lost in wires due to:
a) Heating
b) Resistance
c) Conduction
d) Both a and b
Answer: d
Q. Skip distance depends on time of day and angle of incidence.
a) True
b) False
Answer: a
Q. It is found that ship-to-ship communication suffers from fading. This can be avoided by using:
a) Space diversity
b) Frequency diversity
c) Broadband antenna
d) Directional antenna
Answer: b
Q. A buffer amplifier is:
a) A double-tuned amplifier
b) A high-gain D.C. amplifier
c) A cathode follower stage
d) None of the above
Answer: b
Also Read: Current Electricity
Q. SSB can be generated by:
a) Filter method
b) Phase cancellation method
c) Good attenuation characteristics
d) All of the above
Answer: d
Q. What is the purpose of peak clipper circuits in radio transmitters?
a) To prevent overmodulation
b) To reduce bandwidth
c) To increase bandwidth
d) To regulate oscillator input voltage
Answer: a
Q. In a communication system, noise is most likely to affect the signal:
a) At the transmitter
b) In the channel or transmission line
c) In the information source
d) At the receiver
Answer: b
Q. In short wave communication, waves of which of the following frequencies will be reflected back by the ionospheric layer, having electron density
per m?
a) 2 MHz
b) 10 MHz
c) 12 MHz
d) 18 MHz
Answer: a
Q. Advantage of optical fibre:
a) High bandwidth and EM interference
b) Low bandwidth and EM interference
c) High bandwidth, low transmission capacity and no EM interference
d) High bandwidth, high data transmission capacity and no EM interference
Answer: d
Q. AM is used for broadcasting because:
a) It is more noise-immune than other modulation systems
b) It requires less transmitting power compared with other systems
c) Its use avoids receiver complexity
d) No other modulation system can provide the necessary bandwidth for faithful transmission
Answer: c
Q. The total power content of an AM wave is 1500 W. For 100% modulation, the power transmitted by the carrier is:
a) 500 W
b) 700 W
c) 750 W
d) 1000 W
Answer: d
Q. Through which mode of propagation can radio waves be sent from one place to another?
a) Ground wave propagation
b) Sky wave propagation
c) Space wave propagation
d) All of the above
Answer: d
Q. Audio signal cannot be transmitted because:
a) The signal has more noise
b) The signal cannot be amplified for distance communication
c) The transmitting antenna length is very small to design
d) The transmitting antenna length is very large and impracticable
Answer: d
Q. Long distance short-wave radio broadcasting uses:
a) Ground wave
b) Ionospheric wave
c) Direct wave
d) Sky wave
Answer: c
Q. Maximum useable frequency (MUF) in the F-region layer is x, when the critical frequency is 60 MHz and the angle of incidence is 70°. Then x is:
a) 150 MHz
b) 170 MHz
c) 175 MHz
d) 190 MHz
Answer: c
Q. The bit rate for a signal, which has a sampling rate of 8 kHz and where 16 quantisation levels have been used is:
a) 32000 bits/sec
b) 16000 bits/sec
c) 64000 bits/sec
d) 72000 bits/sec
Answer: a
Q. A laser beam is used for carrying out surgery because it:
a) Is highly monochromatic
b) Is highly coherent
c) Is highly directional
d) Can be sharply focused
Answer: d
Q. An amplitude modulated wave is modulated to 50%. What is the saving in power if the carrier as well as one of the sidebands are suppressed?
a) 70%
b) 65.4%
c) 94.4%
d) 25.5%
Answer: c
Q. Basically, the product modulator is:
a) A mixer
b) An amplifier
c) A frequency separator
d) A phase separator
Answer: a
Q. While tuning in to a certain broadcast station with a receiver, we are actually:
a) Varying the local oscillator frequency
b) Varying the frequency of the radio signal to be picked up
c) Tuning the antenna
d) None of these
Answer: a
Q. In FM radio broadcasting, the frequency deviation is usually:
a) 75 kHz
b) 25 kHz
c) 50 kHz
d) 100 kHz
Answer: a
Q. Noise in a communication system can be reduced by:
a) Increasing bandwidth
b) Increasing signal power
c) Decreasing bandwidth
d) Decreasing signal power
Answer: b
Q. The main function of a repeater in a communication system is to:
a) Attenuate the signal
b) Filter the signal
c) Amplify the signal
d) Modulate the signal
Answer: c
Q. Modulation is used in communication systems to:
a) Increase the bandwidth
b) Decrease the power consumption
c) Reduce noise
d) Increase the range of communication
Answer: d
Q. In a digital communication system, quantisation noise occurs due to:
a) Sampling
b) Modulation
c) Quantisation
d) Encoding
Answer: c
Q. In satellite communication, the uplink frequency is:
a) Higher than the downlink frequency
b) Lower than the downlink frequency
c) Equal to the downlink frequency
d) Twice the downlink frequency
Answer: a
