Optics Question 1081
Question: In a Young’s double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index 4/3 without disturbing the geometrical arrangement, the new fringe width will be
[CBSE PMT 1990]
Options:
A) 0.30 mm
B) 0.40 mm
C) 0.53 mm
D) 450 micron
Show Answer
Answer:
Correct Answer: A
Solution:
$ \beta =\frac{\lambda D}{d};\ \ \therefore B\propto \lambda $
$ \frac{\lambda ‘}{\lambda }=\frac{0.4}{4/3}\Rightarrow \lambda ‘=0.3\ mm $ .
