Optics Question 850
Question: In the ideal double-slit experiment, when a glass- plate (refractive index 1.5) of thickness t is introduced in the path of one of the interfering beams $ (wave-lenght\lambda ) $ , the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is
Options:
A) $ 2\lambda $
B) $ 2\lambda /3 $
C) $ \lambda /3 $
D) $ \lambda $
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Path difference $ =(\mu -1)t=n\lambda $ ; For minimum t, n=1;
$ \therefore t=2\lambda $
