If the highest modulating frequency of the wave is $5\, kHz$,the number of stations that can be accommodated in a $150\, kHz$ bandwidth are

$A$ signal of frequency $3 \text{ kHz}$ is amplitude modulated on a carrier wave of frequency $2.5 \text{ MHz}$. The upper and lower sideband frequencies in the resultant signal are

$A$ transmitting antenna can cover an area of $6.4\pi \times 10^9 \ m^2$ when used for broadcasting. If the signal is transmitted to another antenna,which is at a distance of $100 \ km$ from this antenna,what should be the minimum height of the receiving antenna for satisfactory communication in line-of-sight mode (in $m$)? (Assume the radius of the Earth $R = 6400 \ km$)

In an amplitude modulated wave for an audio frequency of $500 \, \text{cycles/second}$, the appropriate carrier frequency will be ........ $\text{cycles/second}$.

The maximum distance between the transmitting and receiving $TV$ towers is $65 \,km$. If the ratio of the heights of the $TV$ transmitting tower to receiving tower is $36: 49$, the heights of the transmitting and receiving towers respectively are (radius of earth $= 6400 \,km$)

$A$ modulating signal is a square wave,as shown in the figure. If the carrier wave is given as $c(t) = 2 \sin(8 \pi t)$ volts,the modulation index is: