Optics Question 868
Question: In a Young’s double slit experiment with light of wavelength $ \beta $ , fringe pattern on the screen has fringe width $ \beta $ . When two thin transparent glass (refractive index u) plates of thickness $ t _{1} $ and $ t _{2} $ $ (t _{1}>t _{2}) $ are placed in the path of the two beams respectively, the fringe pattern will shift by a distance
Options:
A) $ \frac{\beta (\mu -1)}{\lambda }( \frac{t _{1}}{t _{2}} ) $
B) $ \frac{\mu \beta }{\lambda }\frac{t _{1}}{t _{2}} $
C) $ \frac{\beta (\mu -1)}{\lambda }(t _{1}-t _{2}) $
D) $ (\mu -1)\frac{\lambda }{\beta }(t _{1}+t _{2}) $
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Answer:
Correct Answer: C
Solution:
[c] Shift $ =\frac{\beta (\mu -1)}{\lambda }t _{1}-\frac{\beta (\mu -1)}{\lambda }t _{2} $
$ =\frac{\beta (\mu -1)}{\lambda }(t _{1}-t _{2}) $