Question

The paths difference between two points separated by 1 m in wave of frequency 120 Hz is ${90}^o$ The wave velocity is

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

Answer 1

The correct option is C $480m/s$

The Path difference between the points is given by:

$\Delta =\frac{\lambda }{2\pi }\times \varphi$

$\Rightarrow 1=\frac{\lambda }{2\pi }\times \frac{\pi }{2}$

$\Rightarrow \lambda =4m$

Hence $v=n\lambda$

$=120\times 4=480m/s$