In a line of sight radio communication,a distance of about $50\, km$ is kept between the transmitting and receiving antennas. If the height of the receiving antenna is $70\, m$,then the minimum height of the transmitting antenna should be........$m$ (Radius of the Earth $= 6.4 \times 10^6\, m$)

For $100\%$ modulation,what should be the value of the minimum amplitude $(E_{min})$ of the modulated wave?

If the maximum and minimum voltages of an $A.M.$ wave are $V_{\max}$ and $V_{\min}$ respectively,then the modulation factor '$m$' is

The height of a transmitting antenna at the top of a tower is $25 \; m$ and that of the receiving antenna is $49 \; m$. The maximum distance between them for satisfactory communication in $LOS$ (Line of Sight) is $K \sqrt{5} \times 10^{2} \; m$. The value of $K$ is $\dots$ [Assume radius of Earth is $64 \times 10^{5} \; m$] (Calculate up to the nearest integer value).

For radio and television broadcasting,what type of signals are used to carry information?

The characteristic impedance of a coaxial cable is typically in the range of ..........