A plane mirror is placed at the bottom of the tank containing a liquid of refractive index μ . P is a small object at a height h above the mirror. An observer O-vertically above P outside the liquid see P and its image in the mirror. The apparent distance between these two will be
Image formation by a mirror (either plane or spherical) does not depend on the medium.
The image of P will be formed at a distance h below the mirror. If d = depth of liquid in the tank.
Apparent depth of P=x1=d−hμ
Apparent depth of the image of P=x2=d+hμ
∴ Apparent distance between P and it's image =x2−x1=2hμ