A point object lies 30 cm above water on the axis of a convex mirror of focal length 40 cm lying 20 cm below water surface. Consider two images.

(i) Image formed by the partial reflection from water surface.
(ii) Image formed by refraction from water surface followed by reflection from mirror and again refraction out of the water surface. find the distance between these two images.

Answer

3 cm

Explanation

Image formed by partial reflection from water surface at a distance 30 cm below the air water surface

`because` water surface behaves like a plane mirror secondly image formed by refraction from water surface followed by reflection from mirror and again refraction out of the water surface.
`therefore` Distance of the object from mirror
= u = `20 + (4)/(3) xx 30 implies u = -60`
`therefore v = (-60 xx 40)/(-60 -40) implies v = 24 cm`
Now refrecation from water surface
=`(1)/(v) - (4//3)/((20 + 24)) = (1- 4//3)/(oo) implies v =-33 cm`