Q. The phase difference between two points separated by $1m$ in a wire of frequency $120\ Hz$ is $90^{o}.$ The wave velocity is
A) $180\ m/s$
B) $240\ m/s$
C) $480\ m/s$
D) $720\ m/s$
Explanation
(c) Path difference $\mathrm{\Delta} = \frac{\lambda}{2\pi} \times \phi \Rightarrow 1 = \frac{\lambda}{2\pi} \times \frac{\pi}{2} \Rightarrow \lambda = 4m$
Hence $v = n\lambda = 120 \times 4 = 480\ m/s$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.