Question

Which frequencies is produced if Va  sin⁡(ωa t) amplitude modulates the carrier Vc  sin⁡(ωc t)?

(a) (ωc + ωa), (ωc – ωa) and ωc

(b) (ωc) and (ωa)

(c) (ωc + ωa) and (2ωc + 2ωa)

(d) (2ωc) and (2ωa)

I got this question in an online quiz.

My query is from Spectrum of AM SC Waves in chapter Side Band Techniques of Analog Communications

Answer 1

The correct answer is (a) (ωc + ωa), (ωc – ωa) and ωc

The best I can explain: If we modulate the carrier signal having frequency ωc with respect to the message wave having frequency ωa, then the resultant modulated wave has frequency components  (ωc + ωa), (ωc – ωa) and ωc.