For an amplitude modulated wave, the maximum and minimum amplitudes are found to be 10 V and 2 V respectively. Then, the modulation index is

The process of the loss of strength of a signal while propagating through a medium 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

The heights of the transmitting and receiving antennas are 33.8 m and 64.8 m respectively. The maximum distance between the antennas for satisfactory communication in line of sight mode is (radius of the earth $=6400 \mathrm{~km}$ )