In communication with the help of an antenna,if the height is doubled,then the range covered,which was initially $r$,would become:

If $E_c$ and $E_m$ are peak values of carrier and modulating signals,respectively,then for $100 \%$ modulation,

The process of the loss of strength of a signal while propagating through a medium is known as:

The amplitude of the upper and lower sidebands of an $A.M.$ wave,where a carrier signal with frequency $11.21 \, MHz$ and peak voltage $15 \, V$ is amplitude modulated by a $7.7 \, kHz$ sine wave of $5 \, V$ amplitude,are $\frac{a}{10} \, V$ and $\frac{b}{10} \, V$ respectively. Then the value of $\frac{a}{b}$ is $....$

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 $c = 3 \times 10^8\,m/s$)

$A$ $TV$ tower has a height of $160 \,m$. Its coverage range is nearly (Earth's radius,$R_e = 6400 \,km$):