An $AM$ wave has $1800 \,W$ of total power content. For $100 \%$ modulation, the carrier should have power content equal to: (in $\,W$)

Three signals related to amplitude modulation are shown in the figure. The correct assignment of the signals is

$A$ message signal of peak voltage $12 \ V$ is used to amplitude modulate a carrier signal of frequency $1.2 \ MHz$. The amplitude of the side bands is (in $V$)

$A$ carrier wave of amplitude $15\,V$ is modulated by a sinusoidal baseband signal of amplitude $3\,V$. The ratio of maximum amplitude to minimum amplitude in an amplitude modulated wave is:

$A$ $TV$ transmitting antenna is $128 \ m$ tall. If the receiving antenna is at the ground level,the maximum distance between them for satisfactory communication in line-of-sight mode is (radius of the earth $R_e = 6.4 \times 10^6 \ m$):

What are the primary causes of signal attenuation in an optical fiber?