Question

In a Young’s double slit experiment, the fringe width is found to be $ 2\, mm $ , when light of wavelength $ 6000\, \mathring{A} $ is used. Find the change in fringe width if the whole apparatus is immersed in water of refractive index $ 1.33 $ .

• A. $ 0.5\, mm $
• B. $ 1\, mm $
• C. $ 1.5\, mm $
• D. $ 2\, mm $

Answer 1

Answer: (C)

Fringe width $ \beta =2\, mm =2 \times 10^{-3} m$
$ \lambda =6000\, \mathring{A}$
$ \mu =1.33 $
$\beta' =? $
$\beta'=\frac{\beta}{\mu} $
$=\frac{2}{1.33}=1.5 \,mm$