Question

A travelling wave in a string is represented by $y=3 \sin \left(\frac{\pi}{2} t-\frac{\pi}{4} x\right) .$ The phase difference between two particles separated by a distance $4 \,cm$ is (Take $x$ and $y$ in $cm$ and $t$ in seconds)

• A. $\frac{\pi}{2} rad$
• B. $\frac{\pi}{4} rad$
• C. $\pi rad$
• D. 0

Answer 1

Answer: (C)

$y=3 \sin \left(\frac{\pi}{2} t-\frac{\pi}{4} x\right)$
Take $x =0$ and $x =4 \,cm$
$y_{1}=3 \sin \frac{\pi}{2} t \text { and } y_{2}=3 \sin \frac{\pi}{2} t-\pi$
Phase difference in between the two particles is $\pi$.