The bandwidth of an optical fiber is approximately ........

$A$ message signal of frequency $8 \text{ kHz}$ and peak voltage $12 \text{ V}$ is used to modulate a carrier of frequency $1.2 \text{ MHz}$ and peak voltage $20 \text{ V}$. The modulation index is

If in an amplitude modulated wave,the maximum amplitude is $14 \ V$ and the modulation index is $0.4$,then the amplitude of the carrier wave is (in $V$)

$A$ $TV$ tower has a height of $5 \, m$ in a region of population density $\frac{1000}{\pi}$ per square kilometre. The number of people that can receive the transmission is nearly, (in thousands)

The maximum amplitude of an amplitude modulated wave is $16 \,V$, while the minimum amplitude is $4 \,V$. The modulation index is

The height of an antenna is $500 \ m$. Its range is ........ $km$. (Radius of the Earth is $6400 \ km$)