The wavelength of the carrier waves in a modern optical fiber communication network is close to ........ $nm$.

If a number of sine waves with modulation indices $n_1, n_2, n_3, \dots$ modulate a carrier wave, then the total modulation index $(n)$ of the wave is:

Which of the following statements is $NOT$ true regarding communication through optical fibers?

$A$ $TV$ transmission tower antenna is at a height of $20\, m$. Suppose that the receiving antenna is at:
$(i)$ ground level
$(ii)$ a height of $5\, m$.
The increase in antenna range in case $(ii)$ relative to case $(i)$ is $n\%$.
The value of $n$,to the nearest integer,is .....$\%$

The maximum number of $TV$ signals that can be transmitted along a coaxial cable is

For an amplitude modulated wave,the maximum and minimum amplitudes are $12 \,V$ and $3 \,V$ respectively. Then the modulation index is