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Question 20291
JEE Physics · Hard

Principles of Communication: Amplitude Modulation MCQ

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Amplitude ModulationHardQuestion 20291

Question

An AM signal is represented as v(t) = A_c(1 + μ cos ω_m t)cos ω_c t. The three frequency components present are:
  1. A
    ω_c only
  2. B
    ω_m and ω_c only
  3. C
    ω_c, ω_c + ω_m, and ω_c − ω_m
    Correct
  4. D
    ω_m, ω_c + ω_m, and ω_c − ω_m

Correct answer

ω_c, ω_c + ω_m, and ω_c − ω_m

Explanation

Expanding: v(t) = Accos ωct + (μAc/2)cos(ωc+ωm)t + (μAc/2)cos(ωc−ωm)t. Three components: carrier (ωc), upper sideband (ωc+ωm), lower sideband (ωc−ωm). The message frequency ωm itself does NOT appear.

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