An optical fibre communication system works on a wavelength of $1.3 \mu m$. The number of subscribers it can feed if a channel requires $20 \ kHz$ is:

$A$ telephone link operating at a central frequency of $10\, GHz$ is established. If $1\%$ of this is available,then how many telephone channels can be simultaneously provided,given that each telephone covers a bandwidth of $5\, kHz$?

$A$ 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 voltage $400\, V$. The modulation index and difference between the two sideband frequencies are:

$A$ modulating signal $2 \sin (6.28 \times 10^{6} t)$ is added to the carrier signal $4 \sin (12.56 \times 10^{9} t)$ 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 the band pass filter will be $MHz$.

$A$ message signal is used to modulate a carrier frequency. If the peak voltages of the message signal and carrier signal are increased by $0.1 \%$ and $0.3 \%$ respectively,then the percentage change in the modulation index is

What is the amplitude of the $LSB$ (Lower Side Band) frequency in the $AM$ wave shown in the figure (in $V$)?