Question

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

• A. $0.3$
• B. $0.5$
• C. $0.6$
• D. $0.4$

Answer 1

The correct option is C $0.6$

Maximum amplitude $=E_m+E_c=160$

$E_m+100=160$

$E_m=160-100=60$

Modulation index is given by,

$\mu =\frac{E_m}{E_c}=\frac{60}{100}$

$\mu =0.6$

Remember it is a unitless quantity as it is ratio of two same physical quantities.