Question

If an amplitude modulated wave, the maximum amplitude is $10volts$ and the modulation index is $\frac{2}{3}$, then the minimum amplitude is (in $volts$):

• A. $7$
• B. $9$
• C. $6$
• D. $2$

Answer 1

The correct option is D $2$

Given : Modulation index $m=\frac{2}{3}$

Using $m=\frac{A_m}{A_C}$

$\therefore$ $\frac{2}{3}=\frac{A_m}{A_C}$ $⟹A_C=\frac{3}{2}{A}_m$

Maximum amplitude $=10V$

$\therefore$ $A_C+A_m=10$

OR $\frac{3}{2}{A}_m+A_m=10$ $⟹A_m=4V$

$\therefore$ $A_C=\frac{3}{2}\times 4=6V$

Minimum amplitude $=A_C-A_m=6-4=2V$