Young's double slit experiment is first performed in air and then in a medium other than air. It is found that 8 t h bright fringe in the medium lies where 5 t h dark fringe lies in air. The refractive index of the medium is nearly

Step-by-step solution

In air distance of 5 t h dark fringe is y 1 y 1 = y 5 t h d a r k = 2 × 5 - 1 λ D 2 d = 9 λ D 2 d Also, the distance of 8 t h bright fringe in the medium is y 2 = y 8 t h B r i g h t = 8 λ D μ d y 1 = y 2 (according to question) 9 2 λ D d = 8 λ D μ d μ = 16 9 = 1.78