Question

As amplitude of message signal increases modulation index increases or decreases

Answer 1

increases is ur answer I think..

Answer 2

A is the carrier amplitude. M is the modulation amplitude and is the peak change in the RF amplitude from its unmodulated value. From this it can be seen that for an AM modulation index of 0.5, the modulation causes the signal to increase by a factor of 0.5 and decrease to 0.5 of its original level.