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.
Refractive index of the glass block, μg = 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
