Q. The equation of a simple harmonic wave is given by $y = 6\sin{2\pi(2t - 0.1x)},$ where $x$ and $y$ are in $mm$ and $t$ is in seconds. The phase difference between two particles $2\ mm$ apart at any instant is

A) $54{^\circ}$
B) $72{^\circ}$
C) $18{^\circ}$
D) $36{^\circ}$
Explanation

(b) The equation for a harmonic progressive wave is $y = 6\sin{2\pi(2t - 0.1x)}$
$\Rightarrow y = 6\sin{(4\pi t - 2\pi \times 0.1x)}$ This is of the form
$y = A\sin{(\omega t - kx)}$ where $k = \frac{2\pi}{\lambda}$ $\therefore\lambda = 10mm$
The phase difference for two particles separated by $2\ mm\ is\ \phi = \frac{2\pi}{10} \times 2 \Rightarrow \phi = \frac{2\pi}{5} = 72{^\circ}$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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