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emailanmol

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A vessel of depth H is filled with a non-homogenous liquid whose refractive index varies with y as u=(2 -(y/H)), where y is measured from bottom of the vessel. Find the apparent depth as seen by an observer from above?

(Paraxial approximation is allowed)

RELEVANT EQUATIONS:

We know in paraxial approximation

u1/x=u2/y

Where u1 is refractive index of medium 1, x is object distance from surface, u2 is refractive index of surrounding medium , y2 is apparent depth.

MY ATTEMPT:

I took a differential strip of thickness dy at a height of y from bottom.

its refractive index is

(2-(y/H)-(dy/H)) and refractive index of element just below it is (2-(y/H))

Now,

Lets say that the image of the bottom of the vessel formed by refraction from all strips below this height y be at a distance x from the bottom.

Therefore, Its distance from the strip is y-x.

So using the formulae i mentioned.

(2-y/H)/(y-x)=

[(2-(y/H)-(dy/H))]/[y-x-dx)]

So ydx/H -2dx=-ydy/H+xdy/H.

After this am struck cause I cannot integrate.

I know other ways of solving this problem(mentioned in my textbook), but I want to know what exactly am I doing wrong here?

Any help/inputs will be really appreciated.