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JEE Main

Communication Systems

Physics

Previous Years Questions

MCQ (Single Correct Answer)

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The maximum and minimum voltage of an amplitude modulated signal are $$60 \mathrm{~V}$$ and $$20 \mathrm{~V}$$ respectiv...
JEE Main 2022 (Online) 26th July Evening Shift
A radio can tune to any station in $$6 \,\mathrm{MHz}$$ to $$10 \,\mathrm{MHz}$$ band. The value of corresponding wavele...
JEE Main 2022 (Online) 26th July Morning Shift
In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitudes are found to be 6 V a...
JEE Main 2022 (Online) 25th July Evening 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(...
JEE Main 2022 (Online) 30th June Morning Shift
A baseband signal of 3.5 MHz frequency is modulated with a carrier signal of 3.5 GHz frequency using amplitude modulatio...
JEE Main 2022 (Online) 24th June Morning Shift
A signal of 100 THz frequency can be transmitted with maximum efficiency by :
JEE Main 2022 (Online) 25th June Morning Shift
Match List I with List II .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:soli...
JEE Main 2022 (Online) 25th June Evening Shift
A sinusoidal wave y(t) = 40sin(10 $$\times$$ 106 $$\pi$$t) is amplitude modulated by another sinusoidal wave x(t) = 20si...
JEE Main 2022 (Online) 26th June Evening Shift
Choose the correct statement for amplitude modulation :
JEE Main 2022 (Online) 26th June Morning Shift
We do not transmit low frequency signal to long distances because- (a) The size of the antenna should be comparable to s...
JEE Main 2022 (Online) 27th June Evening Shift
Match List-I with List-II .tg {border-collapse:collapse;border-spacing:0;} .tg td{border-color:black;border-style:soli...
JEE Main 2022 (Online) 28th June Morning Shift
Amplitude modulated wave is represented by $${V_{AM}} = 10\,[1 + 0.4\cos (2\pi \times {10^4}t)\cos (2\pi \times {10^7}...
JEE Main 2022 (Online) 28th June Evening Shift
The TV transmission tower at a particular station has a height of 125 m. For doubling the coverage of its range, the hei...
JEE Main 2022 (Online) 29th June Evening Shift
Only 2% of the optical source frequency is the available channel bandwidth for an optical communicating system operating...
JEE Main 2022 (Online) 29th June Morning Shift
An antenna is mounted on a 400 m tall building. What will be the wavelength of signal that can be radiated effectively b...
JEE Main 2021 (Online) 27th August Evening Shift
A transmitting antenna at top of a tower has a height of 50 m and the height of receiving antenna is 80 m. What is range...
JEE Main 2021 (Online) 26th August Evening Shift
In amplitude modulation, the message signalVm(t) = 10 sin (2$$\pi$$ $$\times$$ 105t) volts and Carrier signalVC(t) = 20 ...
JEE Main 2021 (Online) 25th July Morning Shift
What should be the height of transmitting antenna and the population covered if the television telecast is to cover a ra...
JEE Main 2021 (Online) 22th July Evening Shift
A carrier signal C(t) = 25 sin(2.512 $$\times$$ 1010t) is amplitude modulated by a message signal m(t) = 5 sin(1.57 $$\t...
JEE Main 2021 (Online) 17th March Evening 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) o...
JEE Main 2021 (Online) 16th March Morning Shift
If a message signal of frequency 'fm' is amplitude modulated with a carrier signal of frequency 'fc' and radiated throug...
JEE Main 2021 (Online) 25th February Evening Shift
Given below are two statements :Statement I : A speech signal of 2 kHz is used to modulate a carrier signal of 1 MHz. Th...
JEE Main 2021 (Online) 25th February Morning Slot
In an amplitude modulator circuit, the carrier wave is given by, C(t) = 4 sin(20000 $$\pi $$t) while modulating signal i...
JEE Main 2019 (Online) 12th April Evening Slot
Given below in the the left column are different modes of communication using the kinds of waves given the right column....
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 o...
JEE Main 2019 (Online) 10th April Morning Slot
The physical sizes of the transmitter and receiver antenna in a communication system are :-
JEE Main 2019 (Online) 9th April Evening Slot
A signal Acoswt is transmitted using v0 sin $$\omega $$0t as carrier wave. The correct amplitude modulated (AM) signal i...
JEE Main 2019 (Online) 9th April Morning Slot
In a line of sight radio communication, a distance of about 50 km is kept between the transmitting and receiving antenna...
JEE Main 2019 (Online) 8th April Evening Slot
The wavelength of the carrier waves in a modern optical fiber communication network is close to :
JEE Main 2019 (Online) 8th April Morning Slot
To double the covering range of a TV transmittion tower, its height should be multiplied by :
JEE Main 2019 (Online) 12th January Evening 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) 12th January Morning Slot
An amplitude modulated signal is plotted below : Which one of the following best describes the above signal ? ...
JEE Main 2019 (Online) 11th January Evening 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). Her...
JEE Main 2019 (Online) 11th January Morning Slot
The modulation frequency of an AM radio station is 250 kHz, which is 10% of the carrier wave. If another AM station appr...
JEE Main 2019 (Online) 10th January Evening 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 dista...
JEE Main 2019 (Online) 10th January Morning Slot
In a communication system operating at wavelength 800 nm, only one percent of source frequency is available as signal ba...
JEE Main 2019 (Online) 9th January Evening Slot
A carrier wave of peak voltage 14 V is used for transmitting a message signal. The peak voltage of modulating signal giv...
JEE Main 2018 (Online) 16th April Morning Slot
The carrier frequency of a transmitter is provided by a tank circuit of a coil of inductance 49 $$\mu $$H and a capacita...
JEE Main 2018 (Online) 15th April Evening Slot
The number of amplitude modulted broadcast stations that can be accomodated in a $$300$$ $$kHz$$ band width for the high...
JEE Main 2018 (Online) 15th April Morning Slot
A telephonic communication service is working at carrier frequency of 10 GHz. Only 10% of it is utilized for transmissio...
JEE Main 2018 (Offline)
A signal is to be transmitted through a wave of wavelength $$\lambda $$, using a linear antenna. The length l of the ant...
JEE Main 2017 (Online) 9th 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...
JEE Main 2017 (Online) 8th April Morning Slot
In amplitude modulation, sinusoidal carrier frequency used is denoted by $${\omega _c}$$ and the signal frequency is den...
JEE Main 2017 (Offline)
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 carr...
JEE Main 2016 (Online) 10th 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, ...
JEE Main 2016 (Online) 9th April Morning Slot
Choose the correct statement :
JEE Main 2016 (Offline)
A signal of $$5$$ $$kHz$$ frequency is amplitude modulated on a carrier wave of frequency $$2$$ $$MHz.$$ The frequencies...
JEE Main 2015 (Offline)
A radar has a power of $$1kW$$ and is operating at a frequency of $$10$$ $$GHz.$$ It is located on a mountain top of hei...
AIEEE 2012
This question has Statement - $$1$$ and Statement - $$2$$. Of the four choices given after the statements, choose the on...
AIEEE 2011
Consider telecommunication through optical fibres. Which of the following statements is not true?
AIEEE 2003

Numerical

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The required height of a TV tower which can cover the population of $$6.03$$ lakh is $$h$$. If the average population de...
JEE Main 2022 (Online) 25th July Morning 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, ...
JEE Main 2022 (Online) 24th June Evening 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 d...
JEE Main 2022 (Online) 27th June Morning Shift
A carrier wave with amplitude of 250 V is amplitude modulated by a sinusoidal base band signal of amplitude 150V. The ra...
JEE Main 2021 (Online) 1st September Evening Shift
A bandwidth of 6 MHz is available for A.M. transmission. If the maximum audio signal frequency used for modulating the c...
JEE Main 2021 (Online) 31st August Evening Shift
If the sum of the heights of transmitting and receiving antennas in the line of sight of communication is fixed at 160 m...
JEE Main 2021 (Online) 31st 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 ...
JEE Main 2021 (Online) 27th August Morning Shift
An amplitude modulated wave is represented by Cm(t) = 10(1 + 0.2 cos 12560t) sin(111 $$\times$$ 104t) volts. The modulat...
JEE Main 2021 (Online) 26th August Morning Shift
The maximum amplitude for an amplitude modulated wave is found to be 12V while the minimum amplitude is found to be 3V. ...
JEE Main 2021 (Online) 27th July Evening Shift
The amplitude of upper and lower side bands of A.M. wave where a carrier signal with frequency 11.21 MHz, peak voltage 1...
JEE Main 2021 (Online) 27th July Morning 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 ...
JEE Main 2021 (Online) 25th July Evening 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 ...
JEE Main 2021 (Online) 20th July Morning 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 ...
JEE Main 2021 (Online) 18th March Evening Shift
For VHF signal broadcasting, ___________ km2 of maximum service area will be covered by an antenna tower of height 30 m,...
JEE Main 2021 (Online) 17th March Morning Shift
If the highest frequency modulating a carrier is 5 kHz, then the number of AM broadcast stations accommodated in a 90 kH...
JEE Main 2021 (Online) 26th February Evening Shift
The maximum and minimum amplitude of an amplitude modulated wave is 16V and 8V respectively. The modulation index for th...
JEE Main 2021 (Online) 26th February Morning 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. Th...
JEE Main 2021 (Online) 24th February Evening Slot
An audio signal vm = 20 sin 2$$\pi$$(1500t) amplitude modulates a carrier vc = 80 sin 2$$\pi$$(100,000t).The value of pe...
JEE Main 2021 (Online) 24th February Morning Slot

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