Question

A plane progressive wave has frequency $25Hz$ and amplitude $2.5\times {10}^{-5}$ m and initial phase zero, propagates along the negative x-direction with a velocity of $300m/s$. The phase difference between the oscillations at two points $6m$ apart along the line of propagation is :

• A. $\pi$
• B. $\frac{\pi }{2}$
• C. $2\pi$
• D. $\frac{\pi }{4}$

Answer 1

Answer: (A)

$\pi$

$t=\frac{d}{V}$ $=\frac{6}{300}$ $\Rightarrow t=2\times {10}^{-2}$
$T=\frac{1}{25}$ $=4\times {10}^{-2}$
For $2\pi$ time taken to $T$ and phase difference in $t$
$=\frac{2\pi }{T}\times t$ $=\frac{2\pi }{4\times {10}^{-2}}\times 2\times {10}^{-2}$ $=\pi$