Question

A sound wave of frequency $80$ Hz is traveling with speed $320$ m/s .
(b) find the phase difference between two position separated by $20$ cm at a particular instant.

Answer 1

Hence, frequency $\left(n\right)=80Hz$

speed $\left(V\right)=320m/s$

$\lambda =\frac{v}{n}=\frac{320}{80}=4$

In $400ms$, the distance travelled by particle $={△}^{\ast }=320\times 400\times {10}^{-3}$

So, phase difference $\varphi =2\pi /\lambda {△}^{\ast }$

$=2\pi /320\times 80\times 320\times 400\times {10}^{-3}$

$=64\pi$

$△n=20cm=20\times {10}^{-1}m$

So, $\Psi =\frac{2\pi \times △n}{\lambda }$

$=\frac{2\pi \times 20\times {10}^{-1}}{320}\times 80$

$=\pi$

Phase difference between two points $\pi$