Question

A signal of 5 kHz frequency modulates a carrier of frequency 1 MHz and peak voltage 25 V. If the amplitude at the sidebands of the amplitude modulated signal is 5 V, then the modulation index is

• A. 0.8
• B. 0.6
• C. 0.5
• D. 0.2
• E. 0.4

Answer 1

The correct option is E 0.4

Given, peak voltage of the carrier signal is $V_c=25V$ and

peak voltage of the modulated signal is $V_m=2\times 5=10V$ ( as peak voltage $=2\times$ amplitude of voltage)

Modulation index is defined as, $\mu =\frac{V_m}{V_c}=10/25=0.4$