NCERT Solutions for class 12 Physics | Chapter 15 - Communication Systems

(1) Which of the following is not transducer?
[A] Loudspeaker
[B] Amplifier
[C] Microphone
[D] All
Answer: Amplifier
(2) 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: 5 m

DOWNLOAD CURRENT AFFAIRS PDF FROM APP

Article and Schedule Quiz Start Test!
(3) 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: Neil Armstrong, 1969
(4) 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: electrical signals into sound signals
(5) 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: by superimposing it on undamped electro-magnetic waves
(6) 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: sound signals into electrical signals
(7) The modulation index in amplitude modulation is:
[A] Always zero
[B] Between 0 and 1
[C] Between 1 and ∞
[D] None of these
Answer: Between 1 and ∞
(8) The space waves which are affected seriously by atmospheric conditions are:
[A] MF
[B] HUF
[C] VHF
[D] UHF
Answer: UHF
(9) The area served by an antenna of height 100 m is:
[A] 109
[B] 4 × 109 m²
[C] 6 × 109
[D] 8 × 1010
Answer: 4 × 109 m²
(10) Broadcasting antenna are generally:
[A] Ommi directional type
[B] Vertical type
[C] Horizontal type
[D] None
Answer: Vertical type
(11) 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: 20 Hz to 20 kHz
(12) 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: Leonov 1965
(13) An antenna is:
[A] Inductive
[B] Capacitive
[C] Resistive
[D] A transformer
Answer: Inductive
(14) 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: analog signal
(15) The wavelength of a wave of frequency 10 kHz is:
[A] 30 m
[B] 300 m
[C] 30 km
[D] 300 km
Answer: 30 km
(16) 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: remote sensing
(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: 3 × 108 ms-1
(18) 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: digital signal
(19) 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: digital signal
(20) 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: its use avoids receiver complexity

Take Mock Tests

Missiles Mock Test Start Test!
SSC MTS Mock Test Start Test
IBPS CLERK MOCK TEST Start Test
SSC MTS 2022 JULY 26 Shift 1 (ENGLISH) Start Test!
SSC GD Previous Year Paper 2021 Nov 17 Shift - I (Hindi) Start Test!
SSC CGL Tier - 1 PYP 2022 April 21 Shift- 1 (ENGLISH) Start Test!
MPSC PAPER I MOCK TEST 1 (ENGLISH) Start Test!
IB Security Assistant Mock test 1 (english) Start Test!
UP POLICE CONSTABLE MOCK TEST 1 Start Test!
DELHI POLICE CONSTABLE MOCK TEST 1 (HINDI) Start Test!

Chapters