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In amplitude modulation, sinusoidal carrier frequency used is denoted by ωc and the signal frequency is denoted by ωm. The bandwidth (Δωm) of the signal is such that Δωm << ωc. Which of the following frequencies is not contained in the modulated wave?

1. ωm
2. ωc
3. ωm + ωc
4. ωc - ωm

Correct answer: ωm

Solution

In amplitude modulation, the modulated wave consists of the carrier frequency and sidebands created by the modulation process. The original message signal frequency (ωm) is not present in the modulated wave itself; instead, it is represented by the variations in the amplitude of the carrier frequency.

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