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

$A$ carrier wave of peak voltage $10 \,V$ is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of $80 \%$ (in $\,V$)?

The required height of a $TV$ tower which can cover the population of $6.03$ lakh is $h$. If the average population density is $100$ per square $km$ and the radius of the Earth is $6400 \, km$,then the value of $h$ will be $... \, m$.

If $E_c$ and $E_m$ are peak values of carrier and modulating signals,respectively,then for $100 \%$ modulation,

Ultra high frequency $(UHF)$ band stands for

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