A small object is placed at the center of the bottom of a cylindrical vessel of radius 3 cm and height 4 cm filled completely with water. Consider the ray leaving the vessel through corner. Suppose this ray and the ray along the axis of the vessel is used to trace the image. Find the apparent depth and the ratio of real depth to apparent depth under the assumptions taken. Refractive index of water = 1.33.
Refractive Index of water =
= 1.33
Radius of vessel= 3 cm
Height of vessel= 4 cm
Let the length of BD= 
cm
According to the diagram;
------------ (i)
By using Snell’s law;
Or, 
⇒ 
= 
[
----------- (ii)
From equation (i) and (ii);
The apparent depth = 2.25 cm.
The ratio of real depth to apparent depth= 4:2.25 = 1.78.
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