The height of a $T.V.$ tower is $100 \ m$. What is the population covered by the $T.V.$ broadcast if the average population density around the tower is $1000 \ \text{people}/km^2$?

An amplitude modulated signal consists of a message signal of frequency $1 \text{ kHz}$ and peak voltage of $5 \text{ V}$,modulating a carrier frequency of $1 \text{ MHz}$ and peak voltage of $15 \text{ V}$. The correct description of this signal is

Match Column $A$ (layers in the ionosphere for skywave propagation) with Column $B$ (their height range).

Column $A$	Column $B$
$A$. $D$-layer	$I$. $250-400 \ km$
$B$. $E$-layer	$II$. $170-190 \ km$
$C$. $F_1$-layer	$III$. $95-120 \ km$
$D$. $F_2$-layer	$IV$. $65-75 \ km$

In an $AM$ wave,the total power is $900 \ W$. For $100\%$ modulation,the power transmitted in the sidebands is ... $W$.

For transmission of e.m. wave of audible frequency,these waves are superimposed with waves of

$A$ radar has a power of $1 \ kW$ and is operating at a frequency of $10 \ GHz$. It is located on a mountain top of height $500 \ m$. The maximum distance up to which it can detect an object located on the surface of the earth (Radius of earth $= 6.4 \times 10^6 \ m$) is ....... $km$.