The bandwidth of an audio signal is approximately:

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

If the height of the transmitting tower is increased by $30 \%$,then the area covered by it increases by (in $\%$)

$AM$ is used for broadcasting because...

$A$ 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 range of frequency bands used for standard $AM$ broadcast is