JEE Advanced · 2026 · 17 May 2026 · Paper 2 · Wave Optics

As shown in the figure, a ray

A B

of unpolarized light enters from water of refractive index

n_{w} = 4/3

into a medium of refractive index

n_{p} = 4/ 3

after passing through a glass plate of refractive index

n_{g} = 1.5

and a layer of water. At a particular incident angle

i

the reflected ray

C D

is polarized in the direction as shown in the figure. The value of

i

(in degrees) is:

Answer: 60

Solution

When the reflected ray is polarized, light is incident at Brewster's angle. For a series of parallel interfaces, Snell's law gives

n_{i} sin i = n_{p} sin r

, where

r = 90° - i

at Brewster's angle.

Thus:

\frac{4}{3} sin i = \frac{4}{3} sin (90° - i) = \frac{4}{3} cos i

.

This gives

tan i = 3

, so

i = 60°

JEE Advanced · 2026 · 17 May 2026 · Paper 2 · Numerical answer

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