$A$ carrier is simultaneously modulated by two sine waves with modulation indices of $0.4$ and $0.3$. The resultant modulation index will be

$A$ carrier wave of frequency $1000 \text{ kHz}$ is modulated by an audio signal of frequency $800 \text{ Hz}$. What are the frequencies of the first pair of sidebands?

$A$ transmitter supplies $9 \,kW$ to the aerial when unmodulated. The power radiated when modulated to $40\%$ is........$kW$

$A$ signal emitted by an antenna from a certain point can be received at another point on the Earth's surface in the form of:

$A$ modulating signal $2 \sin (6.28 \times 10^{6} t)$ is added to the carrier signal $4 \sin (12.56 \times 10^{9} t)$ for amplitude modulation. The combined signal is passed through a non-linear square law device. The output is then passed through a band pass filter. The bandwidth of the output signal of the band pass filter will be $MHz$.

In amplitude modulation,the message signal $V_{m}(t) = 10 \sin(2 \pi \times 10^{5} t) \text{ V}$ and the carrier signal $V_{c}(t) = 20 \sin(2 \pi \times 10^{7} t) \text{ V}$. The modulated signal contains the message signal with lower sideband and upper sideband frequencies. Therefore,the bandwidth of the modulated signal is $\alpha \text{ kHz}$. The value of $\alpha$ is: