Question

The maximum amplitude of an amplitude modulated wave is found to be $15\, V$ while its minimum amplitude is found to be $3 \,V$. The modulation index is

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

Answer 1

Answer: (B)

$\frac{2}{3}$

Answer 2

Here, $A_{c} + A_{m}= 15\, V\quad ... \left(i\right)$ $A_{c}- A_{m} = 3\,V \quad...\left(ii\right)$ Solving $\left(i\right)$ and $\left(ii\right)$, we get, $A_{c} = 9 \,V$, $A_{m} = 6\, V$ $\therefore\quad$ Modulation index, $\mu = \frac{A_{m}}{A_{c}} = \frac{6}{9} = \frac{2}{3}$