Verified Solution • 2025–26 Session moderate

QJEEM17Ph34e5: JEE Main 2017 Physics - Class 12 JEEM17Ph34e5 Solution: A signal of frequency 20 kHz and peak voltage of 5 Volt is used …

A signal of frequency 20 kHz and peak voltage of 5 Volt is used to modulate a carrier wave of frequency 1.2 MHz and peak voltage 25 Volts. Choose the correct statement.

Multiple Choice Options

  • A Modulation index = 5, side frequency bands are at 1400 kHz and 1000 kHz
  • B Modulation index = 5, side frequency bands are at 21.2 kHz and 18.8 kHz
  • C Modulation index = 0.8, side frequency bands are at 1180 kHz and 1220 kHz
  • D Modulation index = 0.2, side frequency bands are at 1220 kHz and 1180 kHz

Step-by-Step Verified Solution

Modulation index (m) = VmV0=525=0.2

Given, carrier wave,

Fc = 1.2 × 106 Hz = 1200 kHz

and frequency of modulate wave,

Fm = 20 kHz

∴ Side frequency bands are

F1 = 1200 + 20 = 1220 kHz

F2 = 1200 − 80 = 1180 kHz

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