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A 100 V carrier wave is made to vary between 160 V and 40 V by a modulating signal. What is the modulation index ?

1. 0.5
2. 0.6
3. 0.4
4. 0.3

Correct answer: 0.6

Solution

Modulation index = (Vmax - Vmin)/(Vmax + Vmin) = (160 - 40)/(160 + 40) = 120/200 = 0.6.

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