Question

In Young’s double-slit experiment, the separation between the slits is 3 mm and the distance between the slits and the screen is 1 m. If the wavelength of light used is 6000 Å, calculate the fringe width. What will be the change in the fringe width if the entire apparatus is immersed in a liquid of refractive index 4/3 ?

Answer 1

Data : d = 3 × 10^-3 m, 

D = 1 m, 

λ = 6 × 10^-7 m, 

n = \(\cfrac 43\)

(i) The fringe width,

(ii) Refractive index, n = \(\cfrac λ{λ'}\)

\(\therefore\) λ' = \(\cfrac λ{n}\)

The fringe width in this case is

\(\therefore\) The change in fringe width

= W - W' = (2 - 1.5) x 10^-4 

= 5 x 10^-5 m