Question:
The maximum amplitude of an A.M. wave is found to be 15 V while its minimum amplitude is found to be 3 V. What is the modulation index?
Solution:
Modulation index is defined as the ratio of change of amplitude of carrier wave to the amplitude of the original carrier wave.
The maximum amplitude of AM wave is = Amax = Ac + Am = 15 V
The minimum amplitude of the AM wave is = Amin = Ac – Am = 3V
m = modulation index = Am/Ac = 2/3