The bandwidth of a coaxial cable is approximately ........ .

An $FM$ broadcast transmitter,using a modulating signal of frequency $20\,kHz$,has a deviation ratio of $10$. The bandwidth required for transmission is $.......kHz$.

Statement-$1$: Sky wave signals are used for long-distance radio communication.
Statement-$2$: These signals are generally less stable than ground wave signals.

$A$ signal of $0.1 \, kW$ is transmitted in a cable. The attenuation of the cable is $-5 \, dB$ per $km$ and the cable length is $20 \, km$. The power received at the receiver is $10^{-x} \, W$. The value of $x$ is ....... .
$[\text{Gain in } dB = 10 \log_{10}(\frac{P_0}{P_i})]$

$A$ signal of $20 kHz$ is being carried on a carrier wave of $3 MHz$. What are the side-band frequencies?

$A$ $..........$ is used in the receiver section to reduce the magnitude of signals.