The signal obtained at the output of a microphone is of which type?

$A$ carrier wave of peak voltage $12 \,V$ is used to transmit a signal. If the modulation index is $75 \%$, the peak voltage of the modulating signal is (in $\,V$)

An antenna current of an $AM$ broadcast transmitter modulated by $50\%$ is $11\, A$. The carrier current is.........$A$.

The wavelength of the carrier waves in a modern optical fiber communication network is close to ........ $nm$.

For effective radiation of a wave with a frequency of $20 \text{ MHz}$,what should be the length of the antenna in $m$?

In amplitude modulation of waves,the maximum amplitude is $30 \text{ mV}$ and minimum amplitude is $5 \text{ mV}$,then the modulation index is