Physics | MHT CET 2016 | Discussion Page

A progressive wave is repesented by y= 12 sin (5t-4x) cm. On this wave , how far away are the two points having phase difference of 90° ?

$\frac{\pi}{2}$ cm

$\frac{\pi}{4}$ cm

$\frac{\pi}{8}$ cm

$\frac{\pi}{16}$ cm

Option C

According to question , the progressive wave is represents by y=12 sin (5t-4x) cm

Comparing this equatiuon with standard equation of progressive wave,

$y= A \sin(\omega t-kx)$

So, we have A=12

$\omega$ = 5

$\Rightarrow$ k=4

Here, ( $\omega$ t- kx) is phase difference = $\frac {\pi}{2}$

$\therefore$ 5t-4x = $\frac{\pi}{2}$

When t=0, 4x= $\frac{\pi}{2}$

$\therefore$ x= $\frac{\pi}{8}$ cm

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