For a coaxial cable,the typical repeater spacing is approximately............$km$.

$A$ message signal of frequency $f_m$ is used to modulate a carrier of frequency $f_c$. If the sidebands are $f_1$ and $f_2$, then the ratio $\frac{f_c}{f_m}$ is:

The height of a $T.V.$ tower is $100 \ m$. What is the population covered by the $T.V.$ broadcast if the average population density around the tower is $1000 \ \text{people}/km^2$?

$A$ $100\,m$ long antenna is mounted on a $500\,m$ tall building. The complex can become a transmission tower for waves with $\lambda$ (approx) ........ $m$.

For sky wave propagation of a $10\, MHz$ signal, what should be the minimum electron density in the ionosphere?

In an $AM$ wave,the carrier power is given by: