For television broadcasting,the frequency employed is normally in the range of,

An oscillator is producing $FM$ waves of frequency $2 \text{ kHz}$ with a frequency variation of $10 \text{ kHz}$. What is the modulation index?

For commercial telephonic communication,the frequency range adequate for speech signals 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 ... $W$.

An amplitude modulated wave is represented by $c_m(t)= 10[1+0.6 \sin (1250 t)] \sin (10^8 t)$. Then the modulation index is