Question

A progressive wave of frequency $500\text{Hz}$ is travelling with a velocity $360{\text{ms}}^{-1}$. How far are two points, ${60}^{\circ }$ out of phase with each other ?

• A. $0.06\text{m}$
• B. $0.12\text{m}$
• C. $0.18\text{m}$
• D. $0.24\text{m}$

Answer 1

The correct option is B $0.12\text{m}$

We know, $\lambda =\frac{v}{f}=\frac{360}{500}=0.72\text{m}$
Also, phase difference $\Delta \varphi =\frac{2\pi }{\lambda }\left(\Delta x\right)$
where $\Delta x$ is the path difference between two points.
$\Rightarrow \Delta x=\frac{\Delta \varphi \times \lambda }{2\pi }=\frac{\frac{\pi }{3}\left(0.72\right)}{2\pi }=0.12\text{m}$