JEE Physics Communication System MCQs Set A

Question. A device which provides output in electrical form or it has input in electrical form is called a
(a) Transducer
(b) Receiver
(c) Repeater
(d) Transmitter

Answer: A

Question. Out of the following, which is not an essential element of a communication system?
(a) Transducer
(b) Receiver
(c) Communication channel
(d) Transmitter

Answer: A

Question. Decrease in signal strength due to energy losses is called
(a) Attenuation
(b) Noise
(c) Interference
(d) Distortion

Answer: A

Question. The disturbance or distortion in the transmission and processing of message signals is called
(a) Noise
(b) Attenuation
(c) Interference
(d) None of these

Answer: A

Question. A repeater is a combination of
(a) All of these
(b) Transmitter
(c) AmplifierReceiver
(d) Receiver

Answer: A

Question. The frequency band of FM broadcast is
(a) 88 MHz to 108 MHz
(b) 88 Hz to 88 kHz
(c) None of these
(d) 800 kHz to 8000 MHz

Answer: A

Question. Modulation is necessary
(a) All of these
(b) To avoid mixing up of signals from different transmitters
(c) To increase effective power radiated by antenna
(d) To select suitable size of antenna

Answer: A

Question. A device that connects one computer to another across ordinary telephone lines is called
(a) Modem
(b) None of these
(c) Fax
(d) Transducer

Answer: A

Question. Three waves A, B and C of frequencies 1600 kHz, 5 MHz and 60 MHz, respectively are to be transmitted from one place to another. Which of the following is the most appropriate mode of communication?
(a) A is transmitted via ground wave, B via sky wave and C via space wave
(b) A is transmitted via space wave while B and C are transmitted via sky wave
(c) B and C are transmitted via ground wave while A is transmitted via sky wave
(d) B is transmitted via ground wave while A and C are transmitted via space wave

Answer: A

Question. A speech signal of 3 kHz used to modulate a carrier signal of frequency 1 MHz, using amplitude modulation. The frequencies of the side bands will be
(a) 1.003 MHz and 0.997 MHz
(b) 3001 kHz and 2997 kHz
(c) 1 MHz and 0.997 MHz
(d) 1003 kHz and 1000 kHz

Answer: A

Question. An ‘antenna’ is
(a) Inductive
(b) Capacitative
(c) Resistive above its resonance frequency
(d) None of these

Answer: A

Question. A male voice after modulation-transmission sounds like that of a female to the receiver. The problem is due to
(a) Poor bandwidth selection of amplifiers
(b) Poor selection of carrier frequency
(c) Loss of energy in transmission
(d) Poor selection of modulation index

Answer: A

Question.  A basic communication system consists of
Choose the correct sequence in which these are arranged in a basic communication system
(a) Transmitter B. Information source C. User of information D. Channel E. Receiver
(a) BADEC
(b) BDACE
(c) BEADC
(d) ABCDE

Answer: A

Question. Long distance short-wave radio broad-casting uses
(a) Ionospheric wave
(b) Direct wave
(c) Ground wave
(d) Sky wave

Answer: A

Question. The band width of amplitude modulation is
(a) Double the frequency of audio signal
(b) Double the frequency of carrier wave
(c) Equal to frequency of aduio signal
(d) Half the frequency of carrier wave

Answer: A

Question. Broadcasting antennas are generally
(a) Vertical type
(b) Omnidirectional type
(c) Horizontal type
(d) None of these

Answer: A

Question. For television broadcasting, the frequency employed is normally
(a) 30 - 300 MHz
(b) 30 - 300 GHz
(c) 30 - 300 kHz
(d) 30 - 300 Hz

Answer: A

Question. The sound waves after being converted into electrical waves are not transmitted as such because
(a) They are highly absorbed by the atmosphere
(b) The frequency is not constant
(c) They travel with the speed of sound
(d) The height of antenna has to be increased several times

Answer: A

Question. The process of superimposing signal frequency (i.e., audio wave) on the carrier wave is known as
(a) Modulation
(b) Detection
(c) Reception
(d) Transmission

Answer: A

Question. In an amplitude modulated wave for audio -frequency of 500 cycles/second, the appropriate carrier frequency will be
(a) 50,000 cycles/s
(b) 500 cycles/s
(c) 100 cycles/s
(d) 50 cycles/s

Answer: A

Question. If there were no atmosphere, the average temperature on the surface of earth would be
(a) Lower
(b) Higher
(c) Same as now
(d) 0°C

Answer: A

Question. Radio wave of constant amplitude can be generated with
(a) Oscillator
(b) Rectifier
(c) FET
(d) Filter

Answer: A

Question. Ozone layer above earth’s atmosphere will not
(a) Reflect back radiowaves
(b) Prevent ultraviolet rays from sun
(d) Prevent infrared radiations from sun reaching earth

Answer: A

Question. The radio waves of frequency ranging from 2 MHz to 30 MHz are called
(a) Sky waves
(b) Ground waves
(c) Space waves
(d) None of these

Answer: A

Question. A device which connects one computer to another is known as
(a) Modem
(b) FAX
(c) Laser lazer
(d) Photostat machine

Answer: A

Question. Loss of strength of a signal is known as
(a) Attenuation
(b) Modulation
(c) De-modulation
(d) Noise

Answer: A

Question. Which of the following is an advantage of FM over AM?
(a) Less noise
(b) Larger bandwidth
(c) Can be transmitted to longer distance
(d) More circuit complexity

Answer: A

Question. The process of changing some characteristic of a carrier wave in accordance with the signal to be transmitted is called
(a) Modulation
(b) None of these
(c) Rectification
(d) Amplification

Answer: A

Question. Modulation is done in
(a) Transmitter
(b) Radio receiver
(c) None of these
(d) Communication channel

Answer: A

Question. A ground receiver station is receiving a signal at 500 MHz transmitted from a ground transmitter at a height of 300 m located at a distance of 500 km. It is coming via
(a) Satellite communication
(b) Sky wave
(c) Space wave
(d) Ground wave

Answer: A