Question

A postage stamp kept below a rectangular glass block of refractive index 1.5 when viewed from vertically above it, appears to be raised by 7.0 mm. calculate the thickness of the glass block.

Answer 1

Refractive index of the glass block, μ_g = 1.5

Shift in the image = 7mm or 0.7 cm

Thickness of glass block or real depth =?

Shift = Real depth × (1 - 1/μ)

0.7 = R × (1 - 1/1.5)

R = 0.7 x 1.5/0.5 = 2.1cm