The antenna current of an AM transmitter is 8 A when only carrier is sent but increases to 8.96 A when the carrier is sinusoidally modulated. The percentage modulation is
Answer & explanation
Correct answer: option 4
We know that $(\frac{I_t}{I_c})^2=1+\frac{m^2}{2}$
Here, $I_t= 8.96A$ and $I_c =8A$
$∴(\frac{8.96}{8})^2=1+\frac{m^2}{2}$ or $1.254+1+\frac{m^2}{2}$
or $\frac{m^2}{2}=0.254$
or $m^2=0.508$
or $m=0.71=71\%$