JEE Main · 2022 · 26 Jun 2022 · Shift 2 · Semiconductors

In amplitude modulation, the modulated signal contains three frequency components: the carrier frequency ${\omega }_c$ and two sidebands at ${\omega }_c\pm {\omega }_m$. The amplitude of each sideband is $\frac{\mu A_c}{2}$, where $\mu =\frac{A_m}{A_c}$ is the modulation index. Here, $\mu =\frac{20}{40}=0.5$, so the sideband amplitude is $\frac{0.5\times 40}{2}=10$. The minimum frequency component is the lower sideband at ${\omega }_c-{\omega }_m$, which has amplitude 10.