Q. Two waves of frequencies $20\ Hz$ and $30\ Hz.$ Travels out from a common point. The phase difference between them after $0.6\ sec$ is
A) Aero
B) $\frac{\pi}{2}$
C) $\pi$
D) $\frac{3\pi}{2}$
Explanation
(a) Beats period $= \frac{1}{30 - 20} = 0.1\ sec$
$\mathrm{\Delta}\phi = \frac{2\pi}{T}\Delta t = \frac{2\pi}{0.1} \times 0.6 = 2\pi \times 6 = 12\pi$ or Zero
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.