The figure shows the waveform of an amplitude modulated wave. Its modulation factor is

Communication on ground is through electromagnetic waves of wavelength

$A$ message signal of frequency $10 kHz$ and peak voltage of $15 V$ is used to modulate a carrier frequency of $1 MHz$ and peak voltage of $30 V$. Determine the modulation index.

Mean optical power launched into an $8 \ km$ fibre is $120 \ \mu W$ and mean output power is $4 \ \mu W$,then the overall attenuation is ....... $dB$ (Given $\log 30 = 1.477$)

In the process of modulation,the audio waves are called ...........

$A$ carrier wave of peak voltage $16 \text{ V}$ is used to transmit a signal. If the modulation index is $75 \%$, the peak voltage of the modulating signal is (in $\text{ V}$)