For television broadcasting,the frequency employed is normally in the range of,

What is the advantage of an optical fibre?

Radio waves of constant amplitude are produced by a/an . . . . . . .

The process of increasing the strength of a signal using an electronic circuit is called

$A$ carrier wave of peak voltage $20 V$ is used to transmit a message signal. For getting a modulation index of $60 \%$, the peak voltage of the modulating signal is (in $V$)

For short-distance communication,waves with a frequency of $f$ $MHz$ are reflected back from the ionosphere. If the electron density of the ionosphere is $10^{11} \ m^{-3}$,what is the value of $f$?