wave_mechanics progressive_waves Question 5

Question: At a moment in a progressive wave, the phase of a particle executing S.H.M. is $ \frac{\pi }{3} $ . Then the phase of the particle 15 cm ahead and at the time $ \frac{T}{2} $ will be, if the wavelength is 60 cm

Options:

A) $ \frac{\pi }{2} $

B) $ \frac{2\pi }{3} $

C) Zero

D) $ \frac{5\pi }{6} $

Show Answer

Answer:

Correct Answer: D

Solution:

Let the phase of second particle be $ \varphi $ .

Hence phase difference between two particles is $ \Delta \varphi =\frac{2\pi }{\lambda }\Delta x $

Therefore $ ( \varphi -\frac{\pi }{3} )=\frac{2\pi }{60}\times 15 $

$ \Rightarrow \varphi -\frac{\pi }{3}=\frac{\pi }{2}\Rightarrow \varphi =\frac{5\pi }{6} $