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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 longer wavelength
(b) Effective power radiated by a long wavelength baseband signal would be high
(c) We want to avoid mixing up signals transmitted by different transmitter simultaneously
(d) Low frequency signal can be sent to long distances by superimposing with a high frequency wave as well
Therefore, the most suitable option will be:

The positive feedback is required by an amplifier to act an oscillator. The feedback here means:

The height of a transmitting antenna at the top of a tower is \( 25 \, \text{m} \) and that of receiving antenna is , \( 49 \, \text{m} \). The maximum distance between them, for satisfactory communication in LOS (Line-OF-Sight) is \( K \sqrt{5} \times 10^{2} \, \text{m} \). The value of \( K \) is _______.
(Assume radius of Earth is \( 64 \times 10^{+5} \, \text{m} \) ) [Calculate upto nearest integer value]

A sinusoidal wave \( y(t) = 40 \sin(10 \times 10^{6} \pi t) \) is amplitude modulated by another sinusoidal wave \( x(t) = 20 \sin(1000 \pi t) \). The amplitude of minimum frequency component of modulated signal is:

Find the modulation index of an AM wave having \( 8 \, \text{V} \) variation where maximum amplitude of the AM wave is \( 9 \, \text{V} \).

The TV transmission tower at a particular station has a height of \( 125 \ \text{m} \). For doubling the coverage of its range, the height of the tower should be increased by:

Math List I with List II

Choose the correct answer from the following options:

A modulating signal \( 2\sin\left(6.28\times10^6\right)t \) is added to the carrier signal \( 4\sin\left(12.56\times10^9\right)t \) for amplitude modulation. The combined signal is passed through a non-linear square law device. The output is then passed through a band pass filter. The bandwidth of the output signal of band pass filter will ___ \( \text{MHz} \).

The required height of a TV tower which can cover the popular of \( 6.03 \) lakh is \( h \). If the average population density is \( 100 \) per square \( \text{km} \) and the radius of earth is \( 6400 \, \text{km} \), then the value of \( h \) will be __________ \( \text{m} \).

A FM Broad cast transmitter, unsing modulating signal of frequency \( 20 \, \text{kHz} \) has a deviation ratio of \( 10 \). The Bandwidth required for transmission is:

An antenna is placed in a dielectric medium of dielectric constant \( 6.25 \). If the maximum size of that antenna is \( 5.0 \, \text{mm} \), it can radiate a signal of minimum frequency of _______ \( \text{GHz} \). (Given \( \mu_1 = 1 \) for dielectric medium)

At a particular station, the TV transmission tower has a height of \( 100 \, \text{m} \). To triple its coverage range, height of the tower should be increased to:

In AM modulation, a signal is modulated on a carrier wave such that maximum and minimum amplitudes are found to be \( 6 \, \text{V} \) and \( 2 \, \text{V} \) respectively. The modulation index is:

The maximum and minimum voltage of an amplitude modulated signal are \( 60 \, \text{V} \) and \( 20 \, \text{V} \) respectively. The percentage modulation index will be:

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

Which is the correct ascending order of wavelengths?

Amplitude modulated wave is represented by \( V_{AM} = 10 \left[ 1 + 0.4 \cos \left( 2\pi \times 10^{4} \, t \right) \right] \cos \left( 2\pi \times 10^{7} \, t \right) \). The total bandwidth of the amplitude modulated wave is:

Choose the correct statement for amplitude modulation:

A square wave of the modulating signal is shown in the figure. The carrier wave is given by \( C(t) = 5 \sin(8\pi t)\, \text{Volt} \). The modulation index is:

Match List-I with List-II

Choose the correct answer from the options given below:

Only \( 2\% \) of the optical source frequency is the available channel bandwidth for an optical communicating system operating at \( 1000 \, \text{nm} \). If an audio signal requires a bandwidth of \( 8 \, \text{kHz} \), how many channels can be accommodated for transmission?

A signal of \( 100 \, \text{THz} \) frequency can be transmitted with maximum efficiency by :

A baseband signal of \( 3.5 \, \mathrm{MHz} \) frequency is modulated with a carrier signal of \( 3.5 \, \mathrm{GHz} \) frequency using amplitude modulation method. What should be the minimum size of antenna required to transmit the modulated signal?

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JEE Main 2022 28th July Morning Shift

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