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Question 20327
JEE Physics · Hard

Principles of Communication: Amplitude Modulation MCQ

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Amplitude ModulationHardQuestion 20327

Question

A message signal m(t) = 2 cos(2π×5000t) modulates a carrier A_c cos(2π×10⁶t) in AM with μ = 0.5. The amplitude of each sideband component is:
  1. A
    A_c
  2. B
    A_c/2
  3. C
    μA_c/2 = A_c/4
    Correct
  4. D
    2A_c

Correct answer

μA_c/2 = A_c/4

Explanation

AM: v(t) = Ac[1 + μcos ωmt]cos ωct = Accos ωct + (μAc/2)cos(ωc+ωm)t + (μAc/2)cos(ωc−ωm)t. Each sideband amplitude = μAc/2 = 0.5Ac/2 = Ac/4. Sideband power = (Ac/4)²/2 = Ac²/32.

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