Question
Physics Question on Dual nature of matter
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 (wavelength λ), the intensity at the position where the central maximum occurred previously remains unchanged. The minimum thickness of the glass-plate is
A
2λ
B
32λ
C
3λ
D
λ
Answer
2λ
Explanation
Solution
Path difference due to slab should be integral multiple of λ or
\hspace10mm ? x=n \lambda \, or \, (\mu-1)t=n \lambda n = 1,2,3,..
or \hspace20mm t=\frac{n \lambda}{\mu-1}
For minimum value of t, n = 1
\therefore \hspace20mm t=\frac{\lambda}{\mu-1}=\frac{\lambda}{1.5-1}=2 \lambda