For an amplitude modulated wave,the maximum amplitude is found to be $10 \,V$ while the minimum amplitude is found to be $4 \,V$. The modulation index is

When the angle of incidence is $74^{\circ}$,the critical frequency of the $F$ layer is $50 \text{ MHz}$. What is the Maximum Usable Frequency $(MUF)$ in $\text{ MHz}$ (in $.5$)?

$A$ telephonic communication service is working at a carrier frequency of $10 \ GHz$. Only $10\%$ of it is utilized for transmission. How many telephonic channels can be transmitted simultaneously if each channel requires a bandwidth of $5 \ kHz$?

If the highest frequency modulating a carrier is $5\, kHz$,then the number of $AM$ broadcast stations accommodated in a $90\, kHz$ bandwidth are ....... .

In a communication system,the range for line-of-sight propagation on Earth is $d$ for an antenna height of $h$. If $h$ is doubled,then the new range is:

For the output of an $AM$ detector circuit to follow the envelope of the carrier wave,which condition must be satisfied? ($T_c$ is the time period of the carrier wave.)