Question

A wave of frequency $680\text{Hz}$ has a wave velocity of $340\text{m/s}$ . Find the phase difference between two displacements of a certain point on the wave, whose time difference is $0.002\text{s}$.

• A. $\pi$
• B. $2.7\pi$
• C. $1000\pi$
• D. $\frac{\pi }{2}$

Answer 1

The correct option is B $2.7\pi$

We know that,
Phase difference $\left(\Delta \varphi \right)=\frac{2\pi }{T}\times$ time difference $\left(\Delta t\right)$
$\because f=\frac{1}{T}$ we can re write the above equation as,

$\Delta \varphi =2\pi f\times \left(\Delta t\right)$

From the data given in the question ,
$\Delta \varphi =2\pi \times 680\times 0.002=2.72\pi \approx 2.7\pi$