In Young's double slit experiment if width of the slit is made `(1)/(3)` th times width of fringe becomes n times then n ......

Options

A. 3
B. `(1)/(3)`
C. 9
D. `(1)/(9)`

Answer

A

Explanation

Width of fringe `beta=(lambdaD)/(2d)` here `lambda, D and 2` are constant,
`:. Beta prop (1)/(d)`
`:. (beta_(2))/(beta_(1))=(d_(1))/(d_(2))`
`:. (beta_(2))/(beta_(1))=(d)/((d)/(3))=3`
`:. (n beta_(1))/(beta_(1))=3 " " :. n=3`