Question

Beat phenomenon is physically meaningful only, if

• A. $\mid\omega_1-\omega_2\mid>>\mid\omega_1+\omega_2\mid$
• B. $\mid\omega_1-\omega_2\mid<
• C. $\frac{\omega_1}{\omega_2}<17$
• D. $\mid\omega_1+\omega_2\mid>>\frac{\omega_1}{\omega_2}$

Answer 1

Answer: (B)

$\mid\omega_1-\omega_2\mid<

Answer 2

$y_{1}=\sin w_{1} t$ $y_{2}=\sin w_{2} t$ $y_{1}+y_{2}=A\left(\sin w_{1} t+\sin w_{2} t\right)$ $y=2 A \sin \left(\frac{w_{1}+w_{2}}{2}\right) t \cos \left(\frac{w_{1}-w_{2}}{2}\right) t$ $y=A' \sin w't$ $w '=\frac{ w _{1}+ w _{2}}{2}$ $A '=2 A \cos \left(\frac{ w _{1}- w _{2}}{2}\right) t$ For beat to be meaningful, $\left|w_{1}-w_{2}\right|<