Question

The percentage of the total power carried by the sidebands of the AM wave for tone modulation when the modulation index is 0.3 is:

• A. 30%
• B. 4.3%
• C. 43%
• D. 3%

Hint:

In AM, carrier power is constant; sideband power varies with the square of modulation index.

Answer 1

The Correct Option is C

Step 1: Recall power distribution in AM.
Sideband power $= \dfrac{\mu^2}{2} P_c$, where $\mu$ = modulation index.

Step 2: Apply $\mu = 0.3$.
Percentage power in sidebands = $\dfrac{\mu^2}{2 + \mu^2} \times 100 = \dfrac{0.09}{2.09} \times 100 \approx 43%$.
Final Answer: \[ \boxed{43%} \]