$A$ carrier wave of peak voltage $12 \,V$ is used to transmit a signal. If the modulation index is $75 \%$, the peak voltage of the modulating signal is (in $\,V$)

In a communication system,the process of superimposing a low-frequency signal on a high-frequency wave is known as:

In an $AM$ detector circuit,$R = 2 \text{ k}\Omega$ and $C = 1 \mu\text{F}$. This circuit will demodulate a carrier frequency of ......... $\text{kHz}$ effectively.

$A$ message signal of peak voltage $12 \ V$ is used to amplitude modulate a carrier signal of frequency $1.2 \ MHz$. The amplitude of the side bands is (in $V$)

The height of the transmitting antenna is $180\,m$ and the height of the receiving antenna is $245\,m$. The maximum distance between them for satisfactory communication in line of sight will be .......... $km$ (given $R = 6400\,km$).

Which of the following statements is $NOT$ true regarding communication through optical fibers?