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

For double slit experiment – Angular width for first minima = `(lambda)/(2d) prop lambda`
`(theta)/(theta.)= (lambda)/(lambda.)= (lambda)/((lambda)/(mu))= mu`
`theta.= (theta)/(mu)= (0.2^(@))/((4)/(3))= 0.15^(@)`