Question

What will be the modulation index of this given AM wave?

• A. $\frac{1}{5}$
• B. $\frac{3}{4}$
• C. $\frac{2}{5}$
• D. $\frac{2}{3}$

Answer 1

The correct option is D $\frac{2}{3}$

We know that modulation index is given by $\mu =\frac{A_m}{A_c}$ ,where $A_m$ and $A_c$ are the amplitudes of modulating signal and carrier signal respectively.
As, the amplitudes of modulating signal and carrier signal have not been given to us we can find the value of modulation index by
$\mu =\frac{\left(A_{max}-A_{min}\right)/2}{\left(A_{max}+A_{min}\right)/2}$
Thus from the given AM wave $\mu =\frac{\left(10-2\right)/2}{\left(10+2\right)/2}=\frac{2}{3}$