# Solve this

Question:

A $100 \mathrm{~V}$ carrier wave is made to vary between $160 \mathrm{~V}$ and $40 \mathrm{~V}$ by a modulating signal. What is the modulation index?

1. (1) $0.3$

2. (2) $0.5$

3. (3) $0.6$

4. (4) $0.4$

Correct Option: 3,

Solution:

(3) Maximum amplitude $=\mathrm{E}_{m}+\mathrm{E}_{c}=160$

$E_{m}+100=160$

$E_{m}^{\prime}=160-100=60$

Modulation index,

$\mu=\frac{E_{m}}{E_{c}}=\frac{60}{100}$

$\mu=0.6$