The maximum amplitude of an $AM$ wave is $90 \ V$ and the minimum amplitude is $10 \ V$. What is the amplitude of the modulating wave in the given $AM$ wave (in $V$)?

In amplitude modulation,the amplitude of the carrier wave is $A_c$ and that of the modulating signal is $A_m$. In practice,the ratio of $A_m$ to $A_c$ is kept less than or equal to $1$ to avoid:

If the area covered by an $FM$ radio station is to be tripled,the height of the antenna must be .......

The height of a $TV$ tower is $150 \ m$. If the population density in the area covered by the $TV$ tower is $50 \ \text{lakhs}$, then the population density around the $TV$ tower is ....... $km^{-2}$. (Radius of the Earth is $6.4 \times 10^{6} \ m$)

The process of superimposing a signal frequency onto a carrier wave is known as .......

If a carrier wave $C(t) = A \sin \omega_c t$ is amplitude modulated by a modulating signal $m(t) = A \sin \omega_m t$,then the equation of the modulated signal $[C_m(t)]$ and its modulation index are respectively: