Thursday, 28 January 2021

CBSE Class 12 Physics - MCQ and Online Tests - Unit 15 - Communication Systems

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) 109
(b) 4 × 109
(c) 6 × 109
(d) 8 × 1010

Answer

Answer: (b) 4 × 109


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


 

Share:

0 comments:

Post a Comment

In Article

Definition List

Unordered List

Support