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JEE Communication System PYQs with Solutions

139 previous year questions from Communication System (JEE Main & Advanced Physics) with answers and solutions. Numbered list, year tags, and one-tap solutions — built for serious JEE / NEET practice.

139 questionsPhysics2003–2023Answers + solutions

About Communication System PYQs

Communication System has 139 previous year questions in the Quantrex Academy JEE Main & Advanced Physics bank. The 139 questions in this list come from JEE Main (107) and NTA Abhyas JEE Main (32), spanning 2003 to 2023. Each question opens on its own page with the options, the correct answer and the worked solution where available.

Questions by year (this list)

  • 2023: 23
  • 2022: 22
  • 2021: 24
  • 2020: 33
  • 2019: 13
  • 2018: 5
  • 2017: 3
  • 2016: 3
  • 2015: 1
  • 2014: 3
  • 2013: 3
  • 2012: 4

Communication System questions with solutions

1

The height of transmitting antenna is 180m and the height of the receiving antenna is 245m . The maximum distance between them for satisfactory communication in line of sight will

JEE Main 2023 Solution View → 2

To radiate EM signal of wavelength λ with high efficiency, the antennas should have a minimum size equal to:

JEE Main 2023 Solution View → 3

Match List-I with List-II List-I (Layer of atmosphere) List-II (Approximate height over earth's surface) ( A ) F _ 1 - Layer ( I ) 10km (B) D - Layer (II) 170 - 190km (C)

JEE Main 2023 Solution View → 4

The amplitude of 15sin ( 1000 ) is modulated by 10sin ( 4 ) signal. The amplitude modulated signal contains frequencies of A. 500Hz B. 2Hz C. 250Hz D. 498Hz E. 502Hz Choose the

JEE Main 2023 Solution View → 5

In satellite communication, the uplink frequency band used is:

JEE Main 2023 Solution View → 6

A transmitting antenna is kept on the surface of the earth. The minimum height of receiving antenna required to receive the signal in line of sight at 4km distance from it is x ×

JEE Main 2023 Solution View → 7

A massage signal of frequency 3kHz is used to modulate a carrier signal of frequency 1 . 5MHz . The bandwidth of the amplitude modulated wave is

JEE Main 2023 Solution View → 8

A carrier wave of amplitude 15V is modulated by a sinusoidal base band signal of amplitude 3V . The ratio of maximum amplitude to minimum amplitude in an amplitude modulated wave

JEE Main 2023 Solution View → 9

The power radiated from a linear antenna of length l is proportional to (Given, λ = Wavelength of wave):

JEE Main 2023 Solution View → 10

A TV transmitting antenna is 98m high and the receiving antenna is at the ground level. If the radius of the earth is 6400km, the surface area covered by the transmitting antenna

JEE Main 2023 Solution View → 11

For an amplitude modulated wave the minimum amplitude is 3V , while the modulation index is 60 % . The maximum amplitude of the modulated wave is:

JEE Main 2023 Solution View → 12

By what percentage will the transmission range of a TV tower be affected when the height of the tower is increased by 21 % ?

JEE Main 2023 Solution View → 13

In an amplitude modulation, a modulating signal having amplitude of XV is superimposed with a carrier signal of amplitude YV in first case. Then, in second case, the same

JEE Main 2023 Solution View → 14

Which of the following frequencies does not belong to FM broadcast.

JEE Main 2023 Solution View → 15

Given below are two statements Statement I : For transmitting a signal, size of antenna ( l ) should be comparable to wavelength of signal (at least l = (λ)/(4) in dimension).

JEE Main 2023 Solution View → 16

The amplitude of 15sin ( 1000 ) is modulated by 10sin ( 4 ) signal. The amplitude modulated signal contains frequency (ies) of ( A ) 500Hz ( B ) 2Hz ( C ) 250Hz ( D ) 498Hz ( E )

JEE Main 2023 Solution View → 17

Match List I with List II List I List II A Attenuation I Combination of a receiver and transmitter B Transducer II Process of retrieval of information from the carrier wave at

JEE Main 2023 Solution View → 18

A sinusoidal carrier voltage is amplitude modulated. The resultant amplitude modulated wave has maximum and minimum amplitude of 120Vand80V respectively. The amplitude of each

JEE Main 2023 Solution View → 19

The modulation index for an A.M. wave having maximum and minimum peak to peak voltages of 14mV and 6mV respectively is :

JEE Main 2023 Solution View → 20

If the height of transmitting and receiving antennas are 80m each, the maximum line of sight distance will be : Given : Earth’s radius = 6 . 4 × 10 ^ 6 m .

JEE Main 2023 Solution View → 21

A message signal of frequency 5kHz is used to modulate a carrier signal of frequency 2MHz . The bandwidth for amplitude modulation is:

JEE Main 2023 Solution View → 22

Match List I with List II LIST I LIST II A AM Broadcast I 88 - 108MHz B FM Broadcast II 540 - 1600kHz C Television III 3 . 7 - 4 . 2GHz D Satellite Communication IV 54MHz - 590MHz

JEE Main 2023 Solution View → 23

A modulating signal is a square wave, as shown in the figure. If the carrier wave is given as c(t) = 2sin(8 ) volts, the modulation index is:

JEE Main 2023 Solution View → 24

A modulating signal 2sin(6 . 28 × 10 ^ 6 )t is added to the carrier signal 4sin(12 . 56 × 10 ^ 9 )t for amplitude modulation. The combined signal is passed through a non-linear

JEE Main 2022 Solution View → 25

Find the modulation index of an AM wave having 8V variation where maximum amplitude of the AM wave is 9V .

JEE Main 2022 Solution View → 26

A FM Broad cast transmitter, using modulating signal of frequency 20kHz has a deviation ratio of 10 . The Bandwidth required for transmission is :

JEE Main 2022 Solution View → 27

In the case of amplitude modulation to avoid distortion the modulation index (μ) should be :

JEE Main 2022 Solution View → 28

A square wave of the modulating signal is shown in the figure. The carrier wave is given by C(t) = 5sin(8 ) Volt. The modulation index is

JEE Main 2022 Solution View → 29

At a particular station, the TV transmission tower has a height of 100m . To triple its coverage range, height of the tower should be increased to

JEE Main 2022 Solution View → 30

The maximum and minimum voltage of an amplitude modulated signal are 60V and 20V respectively. The percentage modulation index will be

JEE Main 2022 Solution View → 31

A radio can tune to any station in 6MHz to 10MHz band. The value of corresponding wavelength bandwidth will be

JEE Main 2022 Solution View → 32

In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitude are found to be 6V and 2V respectively. The modulation index is

JEE Main 2022 Solution View → 33

The required height of a TV tower which can cover the population of 6 . 03 lakh is h . If the average population density is 100 per square km and the radius of earth is 6400km

JEE Main 2022 Solution View → 34

The TV transmission tower at a particular station has a height of 125m . For doubling the coverage of its range, the height of the tower should be increased by

JEE Main 2022 Solution View → 35

Only 2 % of the optical source frequency is the available channel bandwidth for an optical communicating system operating at 1000nm . If an audio signal requires a bandwidth of

JEE Main 2022 Solution View → 36

Amplitude modulated wave is represented by V _ AM = 10[1 + 0 . 4cos(2π × 10 ^ 4 t)]cos(2π × 10 ^ 7 t) . The total bandwidth of the amplitude modulated wave is

JEE Main 2022 Solution View → 37

Match List-I with List-II List-I List-II (A) Television signal I. 03KHz (B) Radio signal II. 20KHz (C) High Quality Music III. 02MHz (D) Human speech IV. 06MHz

JEE Main 2022 Solution View → 38

We do not transmit low frequency signal to long distances because (a) The size of the antenna should be comparable to signal wavelength which is unreal solution for a signal of

JEE Main 2022 Solution View → 39

The height of a transmitting antenna at the top of a tower is 25m and that of receiving antenna is, 49m . The maximum distance between them, for satisfactory communication in LOS

JEE Main 2022 Solution View → 40

A sinusoidal wave y(t) = 40sin(10 × 10 ^ 6 ) is amplitude modulated by another sinusoidal wave x(t) = 20sin(1000 ) . The amplitude of minimum frequency component of modulated

JEE Main 2022 Solution View → 41

Choose the correct statement for amplitude modulation

JEE Main 2022 Solution View → 42

Match List I with List II List I List II (A) Facsimile (I) Static Document Image (B) Guided media Channel (II) Local Broadcast Radio (C) Frequency Modulation (III) Rectangular

JEE Main 2022 Solution View → 43

A signal of 100THz frequency can be transmitted with maximum efficiency by

JEE Main 2022 Solution View → 44

An antenna is placed in a dielectric medium of dielectric constant 6 . 25 . If the maximum size of that antenna is 5 . 0mm , it can radiate a signal of minimum frequency of _____

JEE Main 2022 Solution View → 45

A baseband signal of 3 . 5MHz frequency is modulated with a carrier signal of 3 . 5GHz frequency using amplitude modulation method. What should be the minimum size of antenna

JEE Main 2022 Solution View → 46

A carrier wave with amplitude of 250V is amplitude modulated by a sinusoidal base band signal of amplitude 150V . The ratio of minimum amplitude to maximum amplitude for the

JEE Main 2021 Solution View → 47

A bandwidth of 6MHz is available for A . M . transmission. If the maximum audio signal frequency used for modulating the carrier wave is not to exceed 6kHz . The number of

JEE Main 2021 Solution View → 48

If the sum of the heights of transmitting and receiving antennas in the line of sight of communication is fixed at 160m, then the maximum range of LOS communication is _______ km

JEE Main 2021 Solution View → 49

An antenna is mounted on a 400m tall building. What will be the wavelength of signal that can be radiated effectively by the transmission tower upto a range of 44km ?

JEE Main 2021 Solution View → 50

A transmitting antenna has a height of 320m and that of receiving antenna is 2000m . The maximum distance between them for satisfactory communication in line of sight mode is d .

JEE Main 2021 Solution View → 51

A transmitting antenna at top of a tower has a height of 50m , and the height of receiving antenna is, 80m . What is the range of communication for the line of sight (LOS) mode?

JEE Main 2021 Solution View → 52

An amplitude-modulated wave is represented by, C _ m ( t ) = 10 ( 1 + 0 . 2cos12560t ) sin(111 × 10 ^ 4 t)V . The modulating frequency in kHz will be

JEE Main 2021 Solution View → 53

The maximum amplitude for an amplitude modulated wave is found to be 12V while the minimum amplitude is found to be 3V . The modulation index is 0 . 6x where x is _____.

JEE Main 2021 Solution View → 54

The amplitude of upper and lower side bands of AM wave where a carrier signal with frequency 11 . 21MHz, peak voltage 15V is amplitude modulated by a 7 . 7kHz sine wave of 5V

JEE Main 2021 Solution View → 55

A message signal of frequency 20kHz and peak voltage of 20 V is used to modulate a carrier wave of frequency 1MHz and peak voltage of 20 V . The modulation index will be:

JEE Main 2021 Solution View → 56

In amplitude modulation, the message signal V _ m ( t ) = 10sin(2π × 10 ^ 5 t) volts and carrier signal V _ C (t) = 20sin(2π × 10 ^ 7 t) volts. The modulated signal now contains

JEE Main 2021 Solution View → 57

What should be the height of transmitting antenna and the population covered if the television telecast is to cover a radius of 150km ? The average population density around the

JEE Main 2021 Solution View → 58

A carrier wave V _ C ( t ) = 160sin(2π × 10 ^ 6 t) volts is made to vary between V _ max = 200V and V _ min = 120V by a message signal V _ m ( t ) = A _ m sin(2π × 10 ^ 3 t)

JEE Main 2021 Solution View → 59

A TV transmission tower antenna is at a height of 20m . Suppose that the receiving antenna is at. (i) ground level (ii) a height of 5m . The increase in antenna range in case (ii)

JEE Main 2021 Solution View → 60

Match List – I with List – II . List – I List – II (a) 10km height over earth's surface (i) Thermosphere (b) 70km height over earth's surface (ii) Mesosphere (c) 180km

JEE Main 2021 Solution View → 61

A carrier signal C ( t ) = 25sin(2 . 512 × 10 ^ 10 t) is amplitude modulated by a message signal m ( t ) = 5sin(1 . 57 × 10 ^ 8 t) and transmitted through an antenna. What will be

JEE Main 2021 Solution View → 62

For VHF signal broadcasting, _______ km ^ 2 of maximum service area will be covered by an antenna tower of height 30m, if the receiving antenna is placed at ground. Let radius of

JEE Main 2021 Solution View → 63

Two identical antennas mounted on identical towers are separated from each other by a distance of 45km . What should nearly be the minimum height of receiving antenna to receive

JEE Main 2021 Solution View → 64

If the highest frequency modulating a carrier is 5kHz , then the number of AM broadcast stations accommodated in a 90kHz bandwidth are

JEE Main 2021 Solution View → 65

The maximum and minimum amplitude of an amplitude modulated wave is 16V and 8V respectively. The modulation index for this amplitude modulated wave is x × 10 ^ - 2 . The value of

JEE Main 2021 Solution View → 66

If a message signal of frequency f _ m is amplitude modulated with a carrier signal of frequency f _ c and radiated through an antenna, the wavelength of the corresponding signal

JEE Main 2021 Solution View → 67

Given below are two statements: Statement I : A speech signal of 2kHz is used to modulate a carrier signal of 1MHz . The bandwidth requirement for the signal is 4kHz . Statement

JEE Main 2021 Solution View → 68

A signal of 0 . 1kW is transmitted in a cable. The attenuation of cable is - 5dB per km and cable length is 20km . The power received at the receiver is 10 ^ - x W . The value of

JEE Main 2021 Solution View → 69

An audio signal v _ m = 20sin2π(1500t) amplitude modulates a carrier v _ c = 80sin2π(100, 000t) . The value of percent modulation is

JEE Main 2021 Solution View → 70

An amplitude modulated waves is represented by expression v _ m = 5(1 + 0 . 6cos6280t)sin(211 × 10 ^ 4 t)V . The minimum and maximum amplitudes of the amplitudes modulated wave

JEE Main 2020 Solution View → 71

Calculate how much population would be covered by T.V. broadcast if height of TV tower is 100 m and the average population density around the tower is 1000 km ^ - 2 (Take radius

NTA Abhyas JEE Main 2020 Solution View → 72

In optical communication systems operating at 1200nm , only 2 % of the source frequency is available for TV transmission having a bandwidth of 5MHz . The number of TV channels

NTA Abhyas JEE Main 2020 Solution View → 73

A carrier wave of peak voltage 12V is used to transmit a message signal. The peak voltage of the modulating signal in order to have a modulation index of 75 % & is

NTA Abhyas JEE Main 2020 Solution View → 74

The mode of propagation used by short wave broadcast services having a frequency range from a few M Hz up to 30MHz & is

NTA Abhyas JEE Main 2020 Solution View → 75

The length of a dipole antenna for a carrier wave of frequency 6 × 10 ^ 8 Hz is ( take speed of EM wave 3 × 10 ^ 8 ms^ - 1 & )

NTA Abhyas JEE Main 2020 Solution View → 76

Consider telecommunication through optical fibres. Which of the following statements is not true?

NTA Abhyas JEE Main 2020 Solution View → 77

Minimum length of antenna required to transmit a radio signal of frequency 10MHz is equal to

NTA Abhyas JEE Main 2020 Solution View → 78

The maximum frequency for reflection of sky waves from a certain layer of the ionosphere is found to be f _ = 9 ( N _ ) ^ 1 / 2 , where N _ is the maximum electron density at that

NTA Abhyas JEE Main 2020 Solution View → 79

1% of 10 ^ 12 Hz of a satellite link was used for telephony. The number of channels or subscribers if each channel is of 8kHz are

NTA Abhyas JEE Main 2020 Solution View → 80

A radar sends waves towards a distant object and receives the signal reflected by the object. These waves are

NTA Abhyas JEE Main 2020 Solution View → 81

Amplitude modulation is the process of

NTA Abhyas JEE Main 2020 Solution View → 82

An amplitude modulated wave is as given in figure. Calculate the percentage modulation,

NTA Abhyas JEE Main 2020 Solution View → 83

A bandwidth of 10MHz is available for AM transmission. If the maximum audio signal frequency used for modulating the carrier is not to exceed 5kHz, how many stations can be

NTA Abhyas JEE Main 2020 Solution View → 84

What is the modulation index of an FM signal having a carrier swing of 100kHz when the modulating signal has a frequency of 8kHz ?

NTA Abhyas JEE Main 2020 Solution View → 85

A TV tower has a height of 150m . The area of the region covered by the TV broadcast is (radius of earth = 6.4 × 10 ^ 6 m )

NTA Abhyas JEE Main 2020 Solution View → 86

1000kHz carrier wave is amplitude modulated by the signal frequency 200 - 4000Hz . The channel width in this case is

NTA Abhyas JEE Main 2020 Solution View → 87

In optical communication system operating at 1200 nm, only 2 % of the source frequency is available for TV transmission having a bandwidth of 5MHz . The number of TV channels that

NTA Abhyas JEE Main 2020 Solution View → 88

If the height of TV tower is increased by 21% , then the transmission range is enhanced by

NTA Abhyas JEE Main 2020 Solution View → 89

The glass of optical fibre has a refractive index 1. 55 and cladding with another glass of refractive index 1. 51 . When the surrounding medium is air, the numerical aperture will

NTA Abhyas JEE Main 2020 Solution View → 90

The area of the region covered by the TV broadcast, by a TV tower of 100m height is (Take, the radius of the earth, R _ e = 6.4 × 10 ^ 6 m )

NTA Abhyas JEE Main 2020 Solution View → 91

In optical communication systems operating at 1200nm , only 2 % of the source frequency is available for TV transmission having a bandwidth of 5MHz . The number of TV channels

NTA Abhyas JEE Main 2020 Solution View → 92

A T.V. tower has a height of 100m . The population covered by T.V. broadcast is, if the average population density around the tower is 1000people km ^ - 2 .

NTA Abhyas JEE Main 2020 Solution View → 93

The antenna current of an AM transmitter is 8A when only the carrier is sent, but it increases to 8. 93A when the carrier is modulated by a single sine wave. Find the percentage

NTA Abhyas JEE Main 2020 Solution View → 94

A signal wave of frequency 12 kHz is modulated with a carrier wave of frequency 2.51 MHz. The upper and lower side band frequencies are respectively

NTA Abhyas JEE Main 2020 Solution View → 95

What is the value of frequency at which electromagnetic wave must be propagated for the D-region of atmosphere to have a refractive index of 0. 5 ? Electron density for D-region

NTA Abhyas JEE Main 2020 Solution View → 96

If the area to be covered for TV telecast is doubled, then the height of transmitting antenna (TV tower) will have to be

NTA Abhyas JEE Main 2020 Solution View → 97

The height of a TV antenna is 200m . The population density is 4000km^ - 2 . Find the population benefited

NTA Abhyas JEE Main 2020 Solution View → 98

The antenna current of an AM broadcast transmitter which is modulated by 50 % is 11 A . The carrier current is

NTA Abhyas JEE Main 2020 Solution View → 99

The radius of the Earth is 6400 km. If the height of an antenna is 500m , then its range is

NTA Abhyas JEE Main 2020 Solution View → 100

The maximum electron density in the ionosphere in the morning is 10 ^ 10 m^ - 3 . At noon time, it increases to 2 × 10 ^ 10 m^ - 3 . Find the ratio of critical frequency at noon

NTA Abhyas JEE Main 2020 Solution View → 101

In optical communication system operating at 1200 nm, only 2% of the source frequency is available for TV transmission having a bandwidth of 5 MHz. The number of TV channels that

NTA Abhyas JEE Main 2020 Solution View → 102

If a carrier wave of 1000 kHz is used to carry the signal, the length of transmitting antenna will be at least equal to

NTA Abhyas JEE Main 2020 Solution View → 103

In a CE transistor amplifier, the audio signal voltage across the collector resistance of 2kΩ is 2V , if the base resistance is 1kΩ and the current amplification of the transistor

JEE Main 2019 Solution View → 104

A message signal of frequency 100MHz and peak voltage 100V is used execute amplitude modulation on a carrier wave of frequency 300GHz and peak voltage 400V . The modulation index

JEE Main 2019 Solution View → 105

The physical sizes of the transmitter and receiver antenna in a communication system are:

JEE Main 2019 Solution View → 106

A signal Acos is transmitted using ν _ 0 sin ω _ 0 t as carrier wave. The correct amplitude modulated ( AM ) signal is:

JEE Main 2019 Solution View → 107

In a line of sight radio communication, a distance of about 50km is kept between the transmitting and receiving antennas. If the height of the receiving antenna is 70m, then the

JEE Main 2019 Solution View → 108

The wavelength of the carrier waves in a modern optical fiber communication network is close to:

JEE Main 2019 Solution View → 109

To double the covering range of a TV transmitting tower, its height should be multiplied by:

JEE Main 2019 Solution View → 110

A 100V carrier wave is made to vary between 160V and 40V by a modulating signal. What is the modulation index?

JEE Main 2019 Solution View → 111

An amplitude modulated signal is plotted below: Which one of the following best describes the above signal?

JEE Main 2019 Solution View → 112

An amplitude modulated signal is given by V(t)=10[1+0.3 . (2.2 × 10^ 4 t)] (5.5 × 10^ 5 t) . Here t is in seconds. The sideband frequencies (in kHz ) are, [Given π=22 / 7 ]

JEE Main 2019 Solution View → 113

The modulation frequency of an AM radio station is 250kHz, which is 10% of the carrier wave. If another AM station approaches you for license what broadcast frequency will you

JEE Main 2019 Solution View → 114

A TV transmission tower has a height of 140m and the height of the receiving antenna is 40m . What is the maximum distance upto which signals can be broadcasted from this tower in

JEE Main 2019 Solution View → 115

In a communication system operating at wavelength 800nm, only one percent of source frequency is available as signal bandwidth. The number of channels accommodated for

JEE Main 2019 Solution View → 116

A carrier wave of peak voltage 14V is used for transmitting a message signal. The peak voltage of the modulating signal given to achieve a modulation index of 80 % will be:

JEE Main 2018 Solution View → 117

The carrier frequency of a transmitter is provided by a tank circuit of a coil of inductance 49 μ H and a capactiance of 2.5 nF . It is modulated by an audio signal of 12 kHz .

JEE Main 2018 Solution View → 118

The number of amplitude modulated broadcast stations that can be accommodated in a 300 kHz band width for the highest modulating frequency 15 kHz will be:

JEE Main 2018 Solution View → 119

The number of amplitude-modulated broadcast stations that can be accommodated in a 300kHz bandwidth for the highest modulating frequency 15kHz will be:

JEE Main 2018 Solution View → 120

A telephonic communication service is working at a carrier frequency of 10GHz . Only 10 % of it is utilized for transmission. How many telephonic channels can be transmitted

JEE Main 2018 Solution View →
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