The frequency of a $FM$ transmitter without signal input is called

$A$ message signal of peak voltage $12 \ V$ is used to amplitude modulate a carrier signal of frequency $1.2 \ MHz$. The amplitude of the side bands is (in $V$)

The process of recovering the modulating signal from the modulated carrier wave is called:

Assertion $(A)$: Television signals are received through sky-wave propagation.
Reason $(R)$: The ionosphere reflects electromagnetic waves of frequencies in the range $(3-30)$ $MHz$.
Choose the correct option.

At a particular station,the $TV$ transmission tower has a height of $100\,m$. To triple its coverage range,the height of the tower should be increased to ......$m$.

If multiple waves with modulation indices $n_1, n_2, n_3, ...$ modulate a carrier wave,what is the total modulation index of the resulting wave?