Tiêu đề 30. Communication Systems.pdf ✅

30 >c\ko`m COMMUNICATION SYSTEMS Trend Analysis of JEE Main and BITSAT (Year 2010-2018) + , - / -+,+ -+,, -+,- -+,. -+,/ -+,0 -+,1 -+,2 Year N u m ber of Q uestions -+,3 . 0 E@@H\di =DONEduHulk 122430 696 PHYSICS PHYSICS PHYSICS EBD_7418
EduHulk COMMUNICATION SYSTEMS 122696 PHYSICS PHYSICS 431
432 PHYSICS Topic 1: Communication System 1. Communication is the process of (a) keeping in touch (b) exchange information (c) broad casting (d) entertainment by electronics 2. Which of the following is the element of a communication system? (a) Transmitter (b) channel (c) Receiver (d) All of the above 3. A transducer used at the transmitting end, serves the purpose of converting (a) electrical signal to sound form (b) sound signal to electrical form (c) electrical signal to magnetic form (d) sound signal to magnetic form 4. The term channel is used to indicate (a) the amplitude range allocated to a given source (b) the frequency range allocated to a given source (c) the voltage-range allocated to a given source (d) All of the above 5. Buffer amplifier is used at the transmitting end to (a) feed carrier frequency to master oscillator (b) amplify carrier frequency (c) mix modulating signal with carrier frequency (d) isolate master oscillator from other stages of transmitter. 6. The purpose of a detector at the receiving end is (a) to amplify signal (b) to reduce its frequency level (c) to modulate signal (d) to demodulate signal 7. Modem is a short form of (a) modulator-demodulator (b) multiplexer-demultiplexer (c) multivibrator-degenerator (d) None of these 8. Ground wave propagation is possible for (a) low radio frequency over a short range (b) high radio frequency over a short range (c) high radio frequency over a long range (d) low radio frequency over a short range. 9. Long range transmission of TV-signal is done by (a) space-wave (b) sky waves (c) ground wave (d) artificial satellite. 10. Field strength of tropospheric TV signal is proportional to (a) 1 l (b) l (c) 2 1 l (d) l 2 11. Long range propagation is not possible by space wave propagation because (a) height of troposhere is quite small (b) height of troposhere is large (c) troposphere absorbs transmitted wave (d) None of these. 12. Critical frequency that gets reflected back from ionosphere is (a) same for all layers of the ionosphere (b) different for different layers of the ionosphere (c) not dependent on layers of the ionosphere (d) None of these 13. Encoding of signal is required for (a) modulation at transmitting end (b) modulation at receiving end (c) demodulation at receiving end (d) demodulation at transmitting end 14. Communication on ground is through electromagnetic waves of wavelength (a) larger than 600 m (b) between 200 and 600 m (c) between 1 and 5 m (d) between 10 – 3 and 0.1 15. During ground wave propagation the transmitted waves gets attenuated because (a) earth surface absorbs the waves (b) frequency of the waves are too low (c) energy content of these waves are high (d) earth surface offers resistance. 16. Wave obtained on superimposition of audible frequency e.m. wave is known as (a) carrier wave (b) high frequency wave (c) modulating wave (d) modulated wave 17. The AM wave is equivalent to the summation of (a) two sinusoidal waves (b) three sinusoidal waves (c) four sinusoidal waves (d) None of these 18. Frequencies of sideband is (a) 2.50005 × 106 Hz, 2.49995 × 106 Hz (b) 2.505× 106 Hz, 2.495 × 106 Hz (c) 2.505× 106 kHz, 2.495 × 106 kHz (d) 2.505 MHz, 2.495 kHz 19. The process of superimposing signal frequency (i.e., audio wave) on the carrier wave is known as (a) Transmission (b) Reception (c) Modulation (d) Detection Exercise 1 : Topic-wise MCQs EduHulk 122696 PHYSICS PHYSICS EBD_7418