Optics Question 227
Question: A light wave is incident normally over a slit of width $ 24\times {{10}^{-5}}cm $ . The angular position of second dark fringe from the central maxima is $30^o$. What is the wavelength of light
[RPET 1995]
Options:
A) $ 6000{\mathring{A}} $
B) $ 5000{\mathring{A}} $
C) $ 3000{\mathring{A}} $
D) $ 1500{\mathring{A}} $
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Answer:
Correct Answer: A
Solution:
For second dark fringe $ d\sin \theta =2\lambda $
$ \Rightarrow $ $ 24\times {{10}^{-5}}\times {{10}^{-2}}\times \sin 30=2\lambda $
$ \Rightarrow $ $ \lambda =6\times {{10}^{-7}}m=6000{AA} $
BETA
