The need for modulation is

$A$ person tries to broadcast with the same antenna both the signals at $10^7 \,Hz$ and $10^6 \,Hz$. If the receiver at some distance has to receive an equal strength for both the frequencies, then the broadcaster has to approximately increase the signal strength at $10^6 \,Hz$ to $10^7 \,Hz$ by

The modulation index for an $A.M.$ wave having maximum and minimum peak-to-peak voltages of $14\,mV$ and $6\,mV$ respectively is:

In communication with the help of an antenna,if the height is doubled,then the range covered,which was initially $r$,would become:

If the highest modulating frequency of the wave is $5 kHz$,then the number of stations that can be accommodated in a $150 kHz$ bandwidth is

Audio signals cannot be transmitted directly over long distances because: