Question

‘X’ for an AM is the ratio of change in amplitude of the carrier wave to the amplitude of the original carrier wave. Identify ‘X’.

(a) Automatic gain control

(b) Modulation index

(c) Phase index

(d) Amplitude index

This question was posed to me in an online quiz.

My question comes from Communication Systems in section Communication Systems of Physics – Class 12

Answer 1

Right choice is (b) Modulation index

The explanation: The modulation index for an AM wave is defined as the ratio of change in the amplitude of the carrier wave to the amplitude of the original carrier wave.

μ = \(  \frac {(Change \, in \, the \, amplitude \, of \, the \, carrier \, wave)}{(Amplitude \, of \, the \, original \, carrier \, wave)}\).