CBSE Class 12 Physics – MCQ and Online Tests – Unit 15 – Communication Systems
Every year CBSE conducts board exams for 12th standard. These exams are very competitive to all the students. So our website provides online tests for all the 12th subjects. These tests are also very effective and useful for those who preparing for competitive exams like NEET, JEE, CA etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.
These online tests are based on latest CBSE Class 12 syllabus. While attempting these our students can identify the weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly.
CBSE Class 12 Physics – MCQ and Online Tests – Unit 15 – Communication Systems
Question 1.
Digital signals:
(a) deal with all sort of values
(b) can use decimal system
(c) can use binary system
(d) (b) and (c) both
Answer
Answer: (d) (b) and (c) both
Question 2.
Which of the following is not transducer?
(a) Loudspeaker
(b) Amplifier
(c) Microphone
(d) All
Answer
Answer: (b) Amplifier
Question 3.
The space waves which are affected seriously by atmospheric conditions are:
(a) MF
(b) HUF
(c) VHF
(d) UHF
Answer
Answer: (d) UHF
Question 4.
Increase in frequency deviation results into:
(a) increase in noise of FM receiver
(b) decrease in noise of AM receiver
(c) increase in noise of Am receiver
(d) decrease in noise of FM receiver
Answer
Answer: (b) decrease in noise of AM receiver
Question 5.
An antenna is:
(a) Inductive
(b) Capacitive
(c) Resistive
(d) A transformer
Answer
Answer: (a) Inductive
Question 6.
AM is used for broadcasting because:
(a) it is more noise immune than other modulation system
(b) it requires less transmitting power compare with other systems
(c) its use avoids receiver complexity
(d) No other modulation system can provide the necessary bandwidth faithful transmission
Answer
Answer: (c) its use avoids receiver complexity
Question 7.
Broadcasting antenna are generally:
(a) Ommi directional type
(b) Vertical type
(c) Horizontal type
(d) None
Answer
Answer: (b) Vertical type
Question 8.
Who undertook the first space walk and in which year?
(a) Leonov 1965
(b) Neil Armstrong, 1969
(c) Rakesh Sharma. 1998
(d) None of these
Answer
Answer: (a) Leonov 1965
Question 9.
The modulation index in amplitude modulation is:
(a) Always zero
(b) Between 0 and 1
(c) Between 1 and ∞
(d) None of these
Answer
Answer: (c) Between 1 and ∞
Question 10.
The output of a digital computer is an example of:
(a) digital signal
(b) analog signal
(c) both (a) and (b)
(d) neither (a) nor (b)
Answer
Answer: (a) digital signal
Question 11.
The term used “to collect the information about an object and a place without physical contact” is called :
(a) modulation
(b) communication
(c) amplification
(d) remote sensing
Answer
Answer: (d) remote sensing
Question 12.
Name the man who was first to place his foot on the moon and in which year:
(a) Neil Armstrong, 1969
(b) James Van A lien, 1971
(c) Leonov, 1965
(d) None of these
Answer
Answer: (a) Neil Armstrong, 1969
Question 13.
A microphone converts:
(a) sound signals into electrical signals
(b) electrical signals into sound signals
(c) both (a) and (b)
(d) Neither (a) nor (b)
Answer
Answer: (a) sound signals into electrical signals
Question 14.
The wavelength of a wave of frequency 10 kHz is:
(a) 30 m
(b) 300 m
(c) 30 km
(d) 300 km
Answer
Answer: (c) 30 km
Question 15.
A loudspeaker converts:
(a) electrical signals into sound signals
(b) sound signals into electrical signals
(c) both (a) and (b)
(d) neither (a) nor (b)
Answer
Answer: (a) electrical signals into sound signals
Question 16.
The sound produced by a tuning fork is a sort of:
(a) analog signal
(b) digital signal
(c) both (a) and (b)
(d) neither (a) nor (b)
Answer
Answer: (a) analog signal
Question 17.
The velocity of electromagnetic wave is:
(a) 3 × 105 ms-1
(b) 3 × 106 ms-1
(c) 3 × 108 ms-1
(d) 3 × 1010 ms-1
Answer
Answer: (c) 3 × 108 ms-1
Question 18.
The audio frequencies range from:
(a) 20 Hz to 20.000 kHz
(b) 20 Hz to 20 kHz
(c) 20 kHz to 20.000 kHz
(d) None of these
Answer
Answer: (b) 20 Hz to 20 kHz
Question 19.
The length of a half wave dipole at 30 mega-hertz is:
(a) 5 m
(b) 10 m
(c) 25 m
(d) 80 m
Answer
Answer: (a) 5 m
Question 20.
In space communication, the sound waves can be sent from one place to another:
(a) through space
(b) through wires
(c) by superimposing it on undamped electro-magnetic waves
(d) by superimposing it on damped electro-magnetic waves
Answer
Answer: (c) by superimposing it on undamped electro-magnetic waves
Question 21.
The area served by an antenna of height 100 m is:
(a) 109m²
(b) 4 × 109 m²
(c) 6 × 109m²
(d) 8 × 1010m²
Answer
Answer: (b) 4 × 109 m²
Question 22.
The output of a digital computer is an example of:
(a) digital signal
(b) analog signal
(c) both (a) and (b) above
(d) neither (a) nor (b)
Answer
Answer: (a) digital signal
Question 23.
Which is more advantageous?
(a) analog data communication
(b) digital data communication
(c) both (a) and (b) are equally good
(d) depends on the situation
Answer
Answer: (b) digital data communication
Question 24.
Communication channel consists of:
(a) transmission line only
(b) optical fibre only
(c) free space only
(d) All of the above
Answer
Answer: (d) All of the above
Question 25.
Digital signals:
(a) represents values as discrete steps
(b) Do not represents values as discrete steps
(c) represent values steps
(d) represent random steps
Answer
Answer: (a) represents values as discrete steps
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