A mark is made on the bottom of a vessel, over this mark a glass slab of thickness and refractive index is placed. Now water (refractive index ) is poured into the vessel so that the surface of the water is 8 cm above the upper surface of the slab. Looking down normally through the water, the apparent depth of the mark below the surface of the water will be
Step 1. Given data:
The thickness of the glass slab =
Refractive index of glass slab =
Refractive index of water =
Step 2. Formula used:
Refractive index = ,
Where real depth, apparent depth
Step 3. Calculating apparent depth.
Hence ,
Where real depth of water, real depth of glass
Thus, apparent depth =
Thus, the apparent depth of the mark below the surface will be .