Optics Question 864
Question: Two coherent sources separated by distance d are radiating in phase having wavelength X. A detector moves in a big circle around the two sources in the plane of the two sources. The angular position n=4 interference maxima is given as
Options:
A) $ {{\sin }^{-1}}\frac{n\lambda }{d} $
B) $ {{\cos }^{-1}}\frac{4\lambda }{d} $
C) $ {{\tan }^{-1}}\frac{d}{4\lambda } $
D) $ {{\cos }^{-1}}\frac{\lambda }{4d} $
Show Answer
Answer:
Correct Answer: B
Solution:
[b] Path difference, $ \Delta x=S _{1}P-S _{2}P=d\cos \theta $
$ \therefore d\cos \theta =4\lambda $ or $ \cos \theta =(4\lambda /d) $
