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Question:

Show using a proper diagram how unpolarised light can be linearly polarised by reflection from a transparent glass surface. The figure shows a ray of light falling normally on the face AB of an equilateral glass prism having refractive index 3/2, placed in water of refractive index 4/3. Will this ray suffer total internal reflection on striking the face AC?

Solution:

A. When Unpolarised light is incident on a glass surface, the electric vectors that are oscillating along a direction perpendicular to the aligned molecules will pass through. Thus, incident light gets polarised.
B. Total internal reflection on AC, if ic < 60°
μ1Sin ic = μ2sin 90°
(3/2)Sin ic = (4/3)(1)
Sin ic = 8/9
ic = sin⁻¹(8/9)
So ic > 60°
So total internal reflection does not take place