The process of superimposing a message signal on a high-frequency carrier wave is called:

In radio broadcasting,the transmission of sound waves is of the type.............

The process of superimposing a signal frequency onto a carrier wave is known as .......

$A$ telephonic communication service is working at a carrier frequency of $20 GHz$. Only $20 \%$ of it is utilized for transmission. If each channel requires a bandwidth of $5 kHz$,then the number of telephonic channels that can be transmitted simultaneously are

The height of a $T.V.$ tower is $75 \ m$. What is the maximum distance in $km$ up to which $T.V.$ transmission can be received (in $.98$)? (Radius of the Earth $= 6.4 \times 10^6 \ m$).

The amplitude of $15 \sin (1000 \pi t)$ is modulated by $10 \sin (4 \pi t)$ signal. The amplitude modulated signal contains frequencies of
$1. 500\,Hz$
$2. 2\,Hz$
$3. 250\,Hz$
$4. 498\,Hz$
$5. 502\,Hz$
Choose the correct answer from the options given below: