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 1 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 ? `(mu_("water")=4//3)`

Options

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

Answer

C

Explanation

Angular width for first minima is Young.s double slit experiment,
`theta=(lambda)/(a)`
For given value of `a,theta prop lambda`
`(theta)/(theta_(w))=(lambda)/(lambda_(w))=(lambda)/(lambda/(mu))=mu`
`theta_(w)=(theta)/(mu)=(0.2^(@))/(4/(3))=0.15^(@)`