$A$ carrier wave of peak voltage $10 \,V$ 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 $\,V$)?

Which one of the following is not classified as pulse modulation?

$A$ carrier wave $60 \sin(2\pi \times 10^6 t)$ is modulated by a signal $15 \sin(300\pi t)$. The modulation index is: (in $\%$)

$A$ $500\, Hz$ modulating voltage fed into an $FM$ generator produces a frequency deviation of $2.25\, kHz$. If the amplitude of the voltage is kept constant but the frequency is raised to $6\, kHz$,then the new frequency deviation will be.......$kHz$.

For $100\%$ modulation $(AM)$,the useful part of the total power radiated is

For efficient transmission of sound waves of wavelength $\lambda$,the minimum length of the antenna should be.....