Q160 / 160 · AP EAMCET 2022 (08 Jul Shift 2) · Physics
A carrier wave of peak voltage $60 \mathrm{~V}$ is used to transmit a message signal. Then the peak voltage of the modulating signal in order to have a modulation index of $90 \%$ is
- A$30 \mathrm{~V}$
- Correct answerB$54 \mathrm{~V}$
- C$45 \mathrm{~V}$
- D$60 \mathrm{~V}$
Solution
Modulation index,
$\mu=\frac{\text { Amplitude of message } A_M}{\text { Amplitude of carrier } A_C}$
here, $\quad \mu=90 \%=\frac{9}{10}$ and $A_C=60 \mathrm{~V}$
$\therefore \quad \frac{9}{10}=\frac{A_M}{60}$
$\Rightarrow \quad A_M=\frac{9 \times 60}{10}=54 \mathrm{~V}$
So peak voltage of modulating signal is $54 \mathrm{~V}$.
Hence, the correct answer is option: 'B'.