A mica strip and

Given, separation between the slits

The distance between the screen and the slit,

Wavelength of light,

refractive index of mica,

refractive index of polystyrene,

(a)The fringe width is given by

(b) The optical path difference is

Now we know that

Therefore, number of fringe shifts is

This means that there are 25 full fringe shifts from the center with 0.42w shift on one side and (1-0.42) w=0.58w on the other side

Hence, maximum on one side =

And on the other side,