$A$ $25\, m$ long antenna is mounted on an antenna tower. The height of the antenna tower is $75\, m$. The wavelength (in meter) of the signal transmitted by this antenna would be

In amplitude modulation,the amplitude of the $.......$ wave varies in proportion to the instantaneous value of the $.......$ wave.

In a communication system operating at a wavelength of $800\,nm,$ only one percent of the source frequency is available as signal bandwidth. The number of channels accommodated for transmitting $TV$ signals of bandwidth $6\,MHz$ is (Take velocity of light $c = 3 \times 10^8\,m/s$)

If in an amplitude modulated wave,the maximum amplitude is $14 \ V$ and the modulation index is $0.4$,then the amplitude of the carrier wave is (in $V$)

What are the primary causes of signal attenuation in an optical fiber?

$A$ message signal of frequency $3\,kHz$ is used to modulate a carrier signal of frequency $1.5\,MHz$. The bandwidth of the amplitude modulated wave is