In a Young's double slit experiment set up, slits are kept `0.4` mm apart from each other screen is kept 2 m apart from slit. The fringe for a givne monochoromatic light is `0.8mm`. If the whole set up is kept in medium of refractive index `1.6,` the fringe width becomes

Options

A. `0.4 mm`
B. `0.8 mm`
C. `0.5`
D. `0.25 mm`

Answer

C

Explanation

`d=0.4 mm D= 3m beta_(2) =0.8 mm , mu =1.6 beta_(d) = ?`
`mu=(beta_(a))/( beta_(d))`
`:. Beta_(d)=(beta_(a))/( mu)=(0.8)/(1.6)`
` beta_(d)=0.5 mm`