Question

The phase difference between two points separated by 1m in a wave of frequency 120 Hz is ${90}^{\circ }$ . The wave velocity is

• A. 180 m/s
• B. 240 m/s
• C. 480 m/s
• D. 720 m/s

Answer 1

The correct option is C 480 m/s

Path different $\Delta =\frac{\lambda }{2\pi }\times \varphi \Rightarrow 1=\frac{\lambda }{2\pi }\times \frac{\pi }{2}\Rightarrow \lambda =4m$
Hence $v=n\lambda =120\times 4=480$ m/s