Optics Question 1152
Question: If prism angle $ \alpha =1{}^\circ ,\ \mu =1.54, $ distance between screen and prism $ (b)=0.7m, $ distance between prism and source $ a=0.3m,\ \lambda =180\pi \ nm $ then in Fresnal biprism find the value of $ \beta $ (fringe width)
[RPMT 2002]
Options:
A) $ {{10}^{-4}}m $
B) $ {{10}^{-3}}mm $
C) $ {{10}^{-4}}\times \pi m $
D) $ \pi \times {{10}^{-3}}m $
Show Answer
Answer:
Correct Answer: A
Solution:
By using $ \beta =\frac{(a+b)\lambda }{2a(\mu -1)\alpha }=\frac{(0.3+0.7)\times 180\pi \times {{10}^{-9}}}{2\times 0.3(1.54-1)\times ( 1\times \frac{\pi }{180} )} $ = $ {{10}^{-4}}m $
