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JEE Main 20199 AprilMorning Shift
Exam
JEE Main
Year
2019
Date
9 April
Shift
Morning Shift
Subject
Physics
Chapter
Communication System

JEE Main 2019 · 9 April · Morning Shift · Physics · Communication System

A signal Acos is transmitted using ν _ 0 sin ω _ 0 t as carrier...

A signal Acos\omegatAcos\omegat is transmitted using ν0sinω0t{ν}_{0}sin{\omega}_{0}t as carrier wave. The correct amplitude modulated(AM)( AM ) signal is:

Options

  1. Aν0sin[ω0(1+0.01Asin\omegat)t]{ν}_{0}sin [ {\omega}_{0}\left(1 + 0.01Asin\omegat\right)t ]
  2. B(ν0+A)cosωtsinω0t\left({ν}_{0} + A\right)cos\omega tsin{\omega}_{0}t
  3. Cν0sinω0t+Acos\omegat{ν}_{0}sin{\omega}_{0}t + Acos\omegat
  4. Dν0sinω0t+A2sin⁡(ω0−ω)t+A2sin⁡(ω0+ω)t{ν}_{0}sin{\omega}_{0}t + \dfrac{A}{2}\sin \left({\omega}_{0} - \omega\right)t + \dfrac{A}{2}\sin \left({\omega}_{0} + \omega\right)t

Correct answer

D. ν0sinω0t+A2sin⁡(ω0−ω)t+A2sin⁡(ω0+ω)t{ν}_{0}sin{\omega}_{0}t + \dfrac{A}{2}\sin \left({\omega}_{0} - \omega\right)t + \dfrac{A}{2}\sin \left({\omega}_{0} + \omega\right)t

Step-by-step solution

ym=Acos\omegat{y}_{m} = Acos\omegat
yc=V0sinω0t{y}_{c} = {V}_{0}sin{\omega}_{0}t
Modulated signal =(V0+Acos\omegat)sinω0t= \left({V}_{0} + Acos\omegat\right)sin{\omega}_{0}t
=V0sinω0t+Acosωtsinω0t= {V}_{0}sin{\omega}_{0}t + Acos\omega tsin{\omega}_{0}t
=V0sinω0t+A2sin⁡(ω0−ω)t+A2sin⁡(ω0+ω)t= {V}_{0}sin{\omega}_{0}t + \dfrac{A}{2}\sin \left({\omega}_{0} - \omega\right)t + \dfrac{A}{2}\sin \left({\omega}_{0} + \omega\right)t
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