Brewster's angle for light entering from air to water medium is ( μ^w…

The correct answer is Option (3) → \( \tan^{-1}(1.33) \)

Brewster's law: at the polarising angle \( i_B \) the reflected light is completely plane polarised, and the tangent of this angle equals the refractive index of the second medium relative to the first.

    \( \displaystyle \tan i_B = \mu^{w}_{a} = 1.33 \)

    \( \displaystyle i_B = \tan^{-1}(1.33) \)

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Polarisation by Reflection – “… The angle of incidence in this case is called Brewster’s angle and is denoted by i_B. We can see that i_B is related to the refractive index of the denser medium. Since we have i_B + r = π/2, we get from Snell’s law

    \( \displaystyle \mu = \frac{\sin i_B}{\sin r} = \frac{\sin i_B}{\sin(\pi/2 - i_B)} = \frac{\sin i_B}{\cos i_B} = \tan i_B \qquad (10.36) \)

This is known as Brewster’s law.”