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

An optical fibre communication system works on a wavelength of $1.3 \mu m$. The number of subscribers it can feed if a channel requires $20 \ kHz$ is:

In an amplitude modulation with modulation index $0.5$,the ratio of the amplitude of the carrier wave to that of the side band in the modulated wave is

$A$ 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 $MHz$.

An amplitude modulated signal is given by $V(t) = 10[1 + 0.6 \cos(2.2 \times 10^4 t)] \sin(5.5 \times 10^5 t)$, where $t$ is in seconds. The sideband frequencies (in $kHz$) are: [Given $\pi = 22/7$]

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: