Optics Question 859
Question: A broad source of light (I= 680 nm) illuminates normally two glass plates 120 mm long that touch at one end and are separated by a wire 0.034 mm in diameter at the other end. The total number of bright fringes that appear over the 120 mm distance is-
Options:
A) 50
B) 100
C) 200
D) 400
Show Answer
Answer:
Correct Answer: B
Solution:
[b] Constructive interference happens when $ 2t=(m-1/2)\lambda $ .
The minimum value for m=is m=1, the maximum value is the integer portion of $ \frac{2d}{\lambda }+\frac{1}{2}=\frac{2\times 0.034\times {{10}^{-3}}}{680\times {{10}^{-9}}}+\frac{1}{2}=100.5 $
$ {m _{\max }}=100 $
