In a double slit experiment, when light of wavelength 400 nm was used, the angular width of the first minima formed on a screen placed i m away was found to be `0.2^(@)`. What will be the angular width of the first minima if the entire experimental apparatus is immersed in water `(u_("water")=4//3)`

Options

A. `0.1^(@)`
B. `0.266^(@)`
C. `0.15^(@)`
D. `0.05^(@)`

Answer

C

Explanation

`theta=(lambda)/(d) and theta=(lambda)/(d) "but" mu=(lambda)/(lambda.) rArr lambda.=(lambda)/(mu)`
and `(theta.)/(theta)=(lambda.)/(lambda)=(lambda)/(mulambda)=(1)/(mu)`
`theta.=(theta)/(mu)=(0.2)/((mu)/(3))=(0.6)/(4)=0.15^(@)`