Question

If the maximum and minimum voltages of an A.M wave are \( V_{\max} \) and \( V_{\min} \) respectively, then the modulation factor ‘m’ is

• A. \( \frac{V_{\max} + V_{\min}}{V_{\max} . V_{\min}} \)
• B. \( \frac{V_{\max} - V_{\min}}{V_{\max} + V_{\min}} \)
• C. \( \frac{2 V_{\max} V_{\min}}{V_{\max} + V_{\min}} \)
• D. \( \frac{V_{\max} + V_{\min}}{V_{\max} - V_{\min}} \)

Hint:

The modulation index in amplitude modulation measures the extent of variation of the carrier amplitude.

Answer 1

The Correct Option is B

The modulation index (\( m \)) in Amplitude Modulation (A.M) is given by: \[ m = \frac{A_{\text{max}} - A_{\text{min}}}{A_{\text{max}} + A_{\text{min}}} \] where:
- \( A_{\text{max}} \) is the maximum amplitude of the modulated wave.
- \( A_{\text{min}} \) is the minimum amplitude of the modulated wave.
Since voltage is directly proportional to amplitude: \[ m = \frac{V_{\max} - V_{\min}}{V_{\max} + V_{\min}} \] Thus, the correct answer is: \[ \frac{V_{\max} - V_{\min}}{V_{\max} + V_{\min}} \]