Q. A small pin fixed on a table top is viewed from above from a distance of 50 cm. By what distance would the pin appear to be raised if it is viewed from the same point through a 15 cm thick glass slab held parallel to the table? Refractive index of glass = 1.5. Does the answer depend on the location of the slab?

Answer

Actual depth of the pin d = 15cm

The Apparent dept of the pin = d'

A Refractive index of glass μ = 1.5

Ratio of real depth to the apparent depth is equal to the refractive index of glass

i. e.

The distance at which the pin show to be raised=d'-d

15 - 10 = 5 cm

For a small angle of incidence this distance doesn't depend up on the location of the slab.