The process of increasing the strength of a signal using an electronic circuit is called

In amplitude modulation,if a message signal of $5 \ kHz$ is modulated by a carrier wave of frequency $900 \ kHz$,then the frequencies of the side bands are

Given the electric field of a complete amplitude modulated wave as $\vec E = \hat i E_c (1 + \frac{E_m}{E_c} \cos \omega_m t) \cos \omega_c t$,where the subscript $c$ stands for the carrier wave and $m$ for the modulating signal. The frequencies present in the modulated wave are:

The transmission loss per kilometer in an optical fiber is approximately...........$dB$.

Find the modulation index of an $AM$ wave having $8\,V$ variation where maximum amplitude of the $AM$ wave is $9\,V$.

If multiple waves with modulation indices $n_1, n_2, n_3, ...$ modulate a carrier wave,what is the total modulation index of the resulting wave?