The maximum usable frequency $(MUF)$ in the $F$-region layer is $x$,when the critical frequency is $60 \, MHz$ and the angle of incidence is $70^\circ$. Then $x$ is ....... $MHz$.

$A$ signal $A \cos \omega t$ is transmitted using $v_0 \sin \omega_0 t$ as a carrier wave. The correct amplitude modulated $(AM)$ signal is:

Choose the correct statement for amplitude modulation.

In $AM$ transmission,the bandwidth of transmission is $10 \, kHz$ and the carrier frequency is $100 \, kHz$. The sideband frequencies are given by:

Given below in the left column are different modes of communication using the kinds of waves given in the right column.

$A$. Optical Fiber Communication	$P$. Ultrasound
$B$. Radar	$Q$. Infrared Light
$C$. Sonar	$R$. Microwaves
$D$. Mobile Phones	$S$. Radio Waves

From the options given below, find the most appropriate match between entries in the left and the right column.

$A$ wave is represented as $e = 10\,(1 + 6\, \sin(50t)) \sin(10^8t)$. The modulation index is: