Alternating Current Question 9
Question 9 - 30 January - Shift 1
A sinusoidal carrier voltage is amplitude modulated. The resultant amplitude modulated wave has maximum and minimum amplitude of $120 V$ and $80 V$ respectively. The amplitude of each sideband is :
(1) $15 V$
(2) $10 V$
(3) $20 V$
(4) $5 V$
Show Answer
Answer: (2)
Solution:
Formula: Modulation Index
$ \begin{aligned} & A_c+A_m=120 \\ & A_c-A_m=80 \\ & \therefore A_c=100 \\ & A_m=20 \end{aligned} $
Modulation index $=\frac{20}{100}=\frac{1}{5}$
Amplitude of each sideband
$ \begin{aligned} & =\mathrm{A}_{\mathrm{c}} \frac{(\bmod \text { ulation index })}{2} \\ & =100 \times \frac{1}{10}=10 \text { volt } \end{aligned} $
