In an amplitude modulated signal,the maximum amplitude is $15 V$ and the minimum amplitude is $5 V$. The amplitude of the modulating wave will be (in $V$)

For commercial telephonic communication,the frequency range adequate for speech signals is

Define the following terms:
$(a)$ Ground waves
$(b)$ Trade winds

Which of the following is the communication channel in case of radio communication?

Given below are two statements
Statement $I:$ For transmitting a signal,the size of the antenna $(l)$ should be comparable to the wavelength of the signal (at least $l = \frac{\lambda}{4}$ in dimension).
Statement $II:$ In amplitude modulation,the amplitude of the carrier wave remains constant (unchanged).
In the light of the above statements,choose the most appropriate answer from the options given below.

Consider an optical communication system operating at a wavelength of $\lambda \sim 800 \, nm$. If only $1\%$ of the optical source frequency is available for optical communication,how many channels can be accommodated for a bandwidth of $8 \, kHz$?