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?

Solution

Given,
Refractive index of glass = 1.5
Real depth = 15 cm

Image of pin appear through glass slab,

μ = \frac{real depth}{apparent depth}

apparent depth = \frac{real depth (thickness of glass slab)}{μ}

= \frac{15}{1.5} = 10 cm

∴

Image is raised up by = 15 - 10 = 5 cm.

Location of slab will not affect the answer is any way.

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