$A$ carrier wave of peak voltage $15 V$ is used to transmit a message signal. What should be the peak voltage of the modulating signal in order to have a modulation index of $80\%$ (in $V$)?

An $AM$ wave has $1800 \ W$ of total power content. For $100 \%$ modulation,the carrier should have a power content equal to $...... \ W$.

For the output of an $AM$ detector circuit to follow the envelope of the carrier wave,which condition must be satisfied? ($T_c$ is the time period of the carrier wave.)

$A$ basic communication system consists of:
$(A)$ Transmitter $(B)$ Information source $(C)$ User of information $(D)$ Channel $(E)$ Receiver
Choose the correct sequence in which these are arranged in a basic communication system.

The government has divided the frequency range from $30\ MHz$ to $60\ MHz$ between $20$ stations,which are independently beaming their signals. Which of the signals can be beamed by each of the stations?

If a receiving station on the ground is receiving a frequency of $10 \text{ MHz}$, the mode of propagation is...