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Communication Systems · Physics · JEE Main

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MCQ (Single Correct Answer)

JEE Main 2023 (Online) 15th April Morning Shift
The height of transmitting antenna is $180 \mathrm{~m}$ and the height of the receiving antenna is $245 \mathrm{~m}$. The maximum distance between the...
JEE Main 2023 (Online) 13th April Evening Shift
To radiate EM signal of wavelength $$\lambda$$ with high efficiency, the antennas should have a minimum size equal to:
JEE Main 2023 (Online) 13th April Morning Shift
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JEE Main 2023 (Online) 12th April Morning Shift
The amplitude of $$15 \sin (1000 \pi \mathrm{t})$$ is modulated by $$10 \sin (4 \pi \mathrm{t})$$ signal. The amplitude modulated signal contains freq...
JEE Main 2023 (Online) 11th April Evening Shift
In satellite communication, the uplink frequency band used is :
JEE Main 2023 (Online) 11th April Morning Shift
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...
JEE Main 2023 (Online) 10th April Evening Shift
A message signal of frequency $$3 ~\mathrm{kHz}$$ is used to modulate a carrier signal of frequency $$1.5 ~\mathrm{MHz}$$. The bandwidth of the amplit...
JEE Main 2023 (Online) 10th April Morning Shift
A carrier wave of amplitude 15 V is modulated by a sinusoidal base band signal of magnitude 3 V. The ratio of maximum amplitude to minimum amplitude i...
JEE Main 2023 (Online) 8th April Evening Shift
The power radiated from a linear antenna of length $$l$$ is proportional to (Given, $$\lambda=$$ Wavelength of wave):
JEE Main 2023 (Online) 8th April Morning Shift
A TV transmitting antenna is $$98 \mathrm{~m}$$ high and the receiving antenna is at the ground level. If the radius of the earth is $$6400 \mathrm{~k...
JEE Main 2023 (Online) 6th April Evening Shift
For an amplitude modulated wave the minimum amplitude is $$3 \mathrm{~V}$$, while the modulation index is $$60 \%$$. The maximum amplitude of the modu...
JEE Main 2023 (Online) 6th April Morning Shift
By what percentage will the transmission range of a TV tower be affected when the height of the tower is increased by $$21 \%$$ ?
JEE Main 2023 (Online) 1st February Evening Shift
In an amplitude modulation, a modulating signal having amplitude of X Volt is superimposed with a carrier signal of amplitude Y Volt in first case. Th...
JEE Main 2023 (Online) 1st February Morning Shift
Which of the following frequencies does not belong to FM broadcast ?
JEE Main 2023 (Online) 31st January Evening Shift
Given below are two statements : Statement I : For transmitting a signal, size of antenna ( $l$ ) should be comparable to wavelength of signal (at lea...
JEE Main 2023 (Online) 31st January Morning Shift
The amplitude of $$15 \sin (1000 \pi \mathrm{t})$$ is modulated by $$10 \sin (4 \pi \mathrm{t})$$ signal. The amplitude modulated signal contains freq...
JEE Main 2023 (Online) 30th January Evening Shift
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JEE Main 2023 (Online) 30th January Morning Shift
A sinusoidal carrier voltage is amplitude modulated. The resultant amplitude modulated wave has maximum and minimum amplitude of $$120 \mathrm{~V}$$ a...
JEE Main 2023 (Online) 29th January Evening Shift
The modulation index for an A.M. wave having maximum and minimum peak-to-peak voltages of 14 mV and 6 mV respectively is-
JEE Main 2023 (Online) 29th January Morning Shift
If the height of transmitting and receiving antennas are 80 m each, the maximum line of sight distance will be: Given : Earth's radius $$=6.4\times10^...
JEE Main 2023 (Online) 25th January Evening Shift
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JEE Main 2023 (Online) 25th January Morning Shift
A message signal of frequency 5 kHz is used to modulate a carrier signal of frequency 2 MHz. The bandwidth for amplitude modulation is :
JEE Main 2023 (Online) 24th January Evening Shift
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JEE Main 2023 (Online) 24th January Morning Shift
A modulating signal is a square wave, as shown in the figure. If the carrier wave is given as $$\mathrm{c(t) = 2\sin(8\pi t)}$$ volts, the modulation...
JEE Main 2022 (Online) 29th July Morning Shift
Find the modulation index of an AM wave having $$8 \mathrm{~V}$$ variation where maximum amplitude of the AM wave is $$9 \mathrm{~V}$$.
JEE Main 2022 (Online) 28th July Evening Shift
A FM Broadcast transmitter, using modulating signal of frequency 20 kHz has a deviation ratio of 10. The Bandwidth required for transmission is :...
JEE Main 2022 (Online) 28th July Morning Shift
In the case of amplitude modulation to avoid distortion the modulation index $$(\mu)$$ should be :
JEE Main 2022 (Online) 27th July Evening Shift
A square wave of the modulating signal is shown in the figure. The carrier wave is given by $$C(t)=5 \sin (8 \pi t)$$ Volt. The modulation index is : ...
JEE Main 2022 (Online) 27th July Morning Shift
At a particular station, the TV transmission tower has a height of 100 m. To triple its coverage range, height of the tower should be increased to...
JEE Main 2022 (Online) 26th July Evening Shift
The maximum and minimum voltage of an amplitude modulated signal are $$60 \mathrm{~V}$$ and $$20 \mathrm{~V}$$ respectively. The percentage modulation...
JEE Main 2022 (Online) 26th July Morning Shift
A radio can tune to any station in $$6 \,\mathrm{MHz}$$ to $$10 \,\mathrm{MHz}$$ band. The value of corresponding wavelength bandwidth will be :...
JEE Main 2022 (Online) 25th July Evening Shift
In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitudes are found to be 6 V and 2 V respectively. The modul...
JEE Main 2022 (Online) 30th June Morning Shift
A speech signal given by 11 sin(2200 $$\pi$$t) V is used for amplitude modulation with a carrier signal given by 44 sin(6600 $$\pi$$t) V. The minimum ...
JEE Main 2022 (Online) 29th June Evening Shift
The TV transmission tower at a particular station has a height of 125 m. For doubling the coverage of its range, the height of the tower should be inc...
JEE Main 2022 (Online) 29th June Morning Shift
Only 2% of the optical source frequency is the available channel bandwidth for an optical communicating system operating at 1000 nm. If an audio signa...
JEE Main 2022 (Online) 28th June Evening Shift
Amplitude modulated wave is represented by $${V_{AM}} = 10\,[1 + 0.4\cos (2\pi \times {10^4}t)]\cos (2\pi \times {10^7}t)$$. The total bandwidth of ...
JEE Main 2022 (Online) 28th June Morning Shift
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JEE Main 2022 (Online) 27th June Evening Shift
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 unre...
JEE Main 2022 (Online) 26th June Evening Shift
A sinusoidal wave y(t) = 40sin(10 $$\times$$ 106 $$\pi$$t) is amplitude modulated by another sinusoidal wave x(t) = 20sin (1000 $$\pi$$t). The amplitu...
JEE Main 2022 (Online) 26th June Morning Shift
Choose the correct statement for amplitude modulation :
JEE Main 2022 (Online) 25th June Evening Shift
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JEE Main 2022 (Online) 25th June Morning Shift
A signal of 100 THz frequency can be transmitted with maximum efficiency by :
JEE Main 2022 (Online) 24th June Morning Shift
A baseband signal of 3.5 MHz frequency is modulated with a carrier signal of 3.5 GHz frequency using amplitude modulation method. What should be the m...
JEE Main 2021 (Online) 27th August Evening Shift
An antenna is mounted on a 400 m tall building. What will be the wavelength of signal that can be radiated effectively by the transmission tower upto ...
JEE Main 2021 (Online) 26th August Evening Shift
A transmitting antenna at top of a tower has a height of 50 m and the height of receiving antenna is 80 m. What is range of communication for Line of ...
JEE Main 2021 (Online) 25th July Morning Shift
In amplitude modulation, the message signalVm(t) = 10 sin (2$$\pi$$ $$\times$$ 105t) volts and Carrier signalVC(t) = 20 sin(2$$\pi$$ $$\times$$ 107 t)...
JEE Main 2021 (Online) 22th July Evening Shift
What should be the height of transmitting antenna and the population covered if the television telecast is to cover a radius of 150 km? The average po...
JEE Main 2021 (Online) 18th March Morning Shift
Match List - I with List - II.List - I(a) 10 km height over earth's surface(b) 70 km height over earth's surface(c) 180 km height over earth's surface...
JEE Main 2021 (Online) 17th March Evening Shift
A carrier signal C(t) = 25 sin(2.512 $$\times$$ 1010t) is amplitude modulated by a message signal m(t) = 5 sin(1.57 $$\times$$ 108t) and transmitted t...
JEE Main 2021 (Online) 16th March Evening Shift
Two identical antennas mounted on identical towers are separated from each other by a distance of 45 km. What should nearly be the minimum height of r...
JEE Main 2021 (Online) 16th March Morning Shift
A 25 m long antenna is mounted on an antenna tower. The height of the antenna tower is 75 m. The wavelength (in meter) of the signal transmitted by th...
JEE Main 2021 (Online) 25th February Evening Shift
If a message signal of frequency 'fm' is amplitude modulated with a carrier signal of frequency 'fc' and radiated through an antenna, the wavelength o...
JEE Main 2021 (Online) 25th February Morning Shift
Given below are two statements :Statement I : A speech signal of 2 kHz is used to modulate a carrier signal of 1 MHz. The bandwidth requirement for th...
JEE Main 2020 (Online) 2nd September Morning Slot
An amplitude modulated wave is represented by the expression vm = 5(1 + 0.6 cos 6280t) sin(211 × 104 t) volts The minimum and maximum amplitudes of th...
JEE Main 2019 (Online) 12th April Evening Slot
In an amplitude modulator circuit, the carrier wave is given by, C(t) = 4 sin(20000 $$\pi $$t) while modulating signal is given by, m(t) = 2 sin (2000...
JEE Main 2019 (Online) 10th April Morning Slot
A message signal of frequency 100 MHz and peak voltage 100 V is used to execute amplitude modulation on a carrier wave of frequency 300 GHz and peak v...
JEE Main 2019 (Online) 10th April Morning Slot
Given below in the the left column are different modes of communication using the kinds of waves given the right column. .tg {border-collapse:collap...
JEE Main 2019 (Online) 9th April Evening Slot
The physical sizes of the transmitter and receiver antenna in a communication system are :-
JEE Main 2019 (Online) 9th April Morning Slot
A signal Acoswt is transmitted using v0 sin $$\omega $$0t as carrier wave. The correct amplitude modulated (AM) signal is
JEE Main 2019 (Online) 8th April Evening Slot
In a line of sight radio communication, a distance of about 50 km is kept between the transmitting and receiving antennas. If the height of the receiv...
JEE Main 2019 (Online) 8th April Morning Slot
The wavelength of the carrier waves in a modern optical fiber communication network is close to :
JEE Main 2019 (Online) 12th January Evening Slot
To double the covering range of a TV transmittion tower, its height should be multiplied by :
JEE Main 2019 (Online) 12th January Morning Slot
A 100 V carrier wave is made to vary between 160 V and 40 V by a modulating signal. What is the modulation index ?
JEE Main 2019 (Online) 11th January Evening Slot
An amplitude modulated signal is plotted below : Which one of the following best describes the above signal ? ...
JEE Main 2019 (Online) 11th January Morning Slot
An amplitude modulated signal is given by V(t) = 10[1 + 0.3cos(2.2 $$ \times $$ 104 t)] sin(5.5 $$ \times $$ 105 t). Here t is in seconds. The sideban...
JEE Main 2019 (Online) 10th January Evening Slot
The modulation frequency of an AM radio station is 250 kHz, which is 10% of the carrier wave. If another AM station approaches you for license what br...
JEE Main 2019 (Online) 10th January Morning Slot
A TV transmission tower has a height of 140 m and the height of the receiving antenna is 40 m. What is the maximum distance upto which signals can be ...
JEE Main 2019 (Online) 9th January Evening Slot
In a communication system operating at wavelength 800 nm, only one percent of source frequency is available as signal bandwith. The number of channels...
JEE Main 2018 (Online) 16th April Morning Slot
A carrier wave of peak voltage 14 V is used for transmitting a message signal. The peak voltage of modulating signal given to achieve a modulation ind...
JEE Main 2018 (Offline)
A telephonic communication service is working at carrier frequency of 10 GHz. Only 10% of it is utilized for transmission. How many telephonic channel...
JEE Main 2018 (Online) 15th April Evening Slot
The carrier frequency of a transmitter is provided by a tank circuit of a coil of inductance 49 $$\mu $$H and a capacitance of 2.5 nF. It is modulated...
JEE Main 2018 (Online) 15th April Morning Slot
The number of amplitude modulted broadcast stations that can be accomodated in a $$300$$ $$kHz$$ band width for the highest modulating frequency $$15$...
JEE Main 2017 (Online) 9th April Morning Slot
A signal is to be transmitted through a wave of wavelength $$\lambda $$, using a linear antenna. The length l of the antenna and effective power radia...
JEE Main 2017 (Online) 8th April Morning Slot
A signal of frequency 20 kHz and peak voltage of 5 Volt is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25 Volts. Choose the ...
JEE Main 2017 (Offline)
In amplitude modulation, sinusoidal carrier frequency used is denoted by $${\omega _c}$$ and the signal frequency is denoted by $${\omega _m}$$. The b...
JEE Main 2016 (Online) 10th April Morning Slot
A modulated signal Cm(t) has the form Cm(t) = 30 sin 300 $$\pi $$t + 10 (cos 200 $$\pi $$t −cos 400 $$\pi $$t). The carrier frequency c, the modulatin...
JEE Main 2016 (Online) 9th April Morning Slot
An audio signal consists of two distinct sounds : one a human speech signal in the frequency band of 200 Hz to 2700 Hz, while the other is a high freq...
JEE Main 2016 (Offline)
Choose the correct statement :
JEE Main 2015 (Offline)
A signal of $$5$$ $$kHz$$ frequency is amplitude modulated on a carrier wave of frequency $$2$$ $$MHz.$$ The frequencies of the resultant signal is/ar...
AIEEE 2012
A radar has a power of $$1kW$$ and is operating at a frequency of $$10$$ $$GHz.$$ It is located on a mountain top of height $$500$$ $$m.$$ The maximum...
AIEEE 2011
This question has Statement - $$1$$ and Statement - $$2$$. Of the four choices given after the statements, choose the one that best describes the two ...
AIEEE 2003
Consider telecommunication through optical fibres. Which of the following statements is not true?

Numerical

JEE Main 2022 (Online) 29th July Evening Shift
A modulating signal $$2 \sin \left(6.28 \times 10^{6}\right) t$$ is added to the carrier signal $$4 \sin \left(12.56 \times 10^{9}\right) t$$ for ampl...
JEE Main 2022 (Online) 25th July Morning Shift
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 $$\mat...
JEE Main 2022 (Online) 27th June Morning Shift
The height of a transmitting antenna at the top of a tower is 25 m and that of receiving antenna is, 49 m. The maximum distance between them, for sati...
JEE Main 2022 (Online) 24th June Evening Shift
An antenna is placed in a dielectric medium of dielectric constant 6.25. If the maximum size of that antenna is 5.0 mm, it can radiate a signal of min...
JEE Main 2021 (Online) 1st September Evening Shift
A carrier wave with amplitude of 250 V is amplitude modulated by a sinusoidal base band signal of amplitude 150V. The ratio of minimum amplitude to ma...
JEE Main 2021 (Online) 31st August Evening Shift
A bandwidth of 6 MHz is available for A.M. transmission. If the maximum audio signal frequency used for modulating the carrier wave is not to exceed 6...
JEE Main 2021 (Online) 31st August Morning Shift
If the sum of the heights of transmitting and receiving antennas in the line of sight of communication is fixed at 160 m, then the maximum range of LO...
JEE Main 2021 (Online) 27th August Morning Shift
A transmitting antenna has a height of 320 m and that of receiving antenna is 2000 m. The maximum distance between them for satisfactory communication...
JEE Main 2021 (Online) 26th August Morning Shift
An amplitude modulated wave is represented by Cm(t) = 10(1 + 0.2 cos 12560t) sin(111 $$\times$$ 104t) volts. The modulating frequency in kHz will be ....
JEE Main 2021 (Online) 27th July Evening Shift
The maximum amplitude for an amplitude modulated wave is found to be 12V while the minimum amplitude is found to be 3V. The modulation index is 0.6x w...
JEE Main 2021 (Online) 27th July Morning Shift
The amplitude of upper and lower side bands of A.M. wave where a carrier signal with frequency 11.21 MHz, peak voltage 15 V is amplitude modulated by ...
JEE Main 2021 (Online) 25th July Evening Shift
A message signal of frequency 20 kHz and peak voltage of 20 volt is used to modulate a carrier wave of frequency 1 MHz and peak voltage of 20 volt. T...
JEE Main 2021 (Online) 20th July Morning Shift
A carrier wave Vc(t) = 160 sin(2$$\pi$$ $$\times$$ 106t) volts is made to vary between Vmax = 200 V and Vmin = 120 V by a message signal Vm(t) = Am si...
JEE Main 2021 (Online) 18th March Evening Shift
A TV transmission tower antenna is at a height of 20 m. Suppose that the receiving antenna is at.(i) ground level(ii) a height of 5 m.The increase in ...
JEE Main 2021 (Online) 17th March Morning Shift
For VHF signal broadcasting, ___________ km2 of maximum service area will be covered by an antenna tower of height 30 m, if the receiving antenna is p...
JEE Main 2021 (Online) 26th February Evening Shift
If the highest frequency modulating a carrier is 5 kHz, then the number of AM broadcast stations accommodated in a 90 kHz bandwidth are _________.
JEE Main 2021 (Online) 26th February Morning Shift
The maximum and minimum amplitude of an amplitude modulated wave is 16V and 8V respectively. The modulation index for this amplitude modulated wave is...
JEE Main 2021 (Online) 24th February Evening Shift
A signal of 0.1 kW is transmitted in a cable. The attenuation of cable is $$-$$5 dB per km and cable length is 20 km. The power received at receiver i...
JEE Main 2021 (Online) 24th February Morning Shift
An audio signal vm = 20 sin 2$$\pi$$(1500t) amplitude modulates a carrier vc = 80 sin 2$$\pi$$(100,000t).The value of percent modulation is _________....
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