Polarisation — Wave Optics — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Polarisation — Wave Optics.

Combined Malus's Law and multiple polarisers

high

This is a classic and versatile problem type. NEET often tests the application of Malus's Law in scenarios involving two or three polarisers, where the angle between successive polarisers needs to be carefully considered. Students might be asked to find the final intensity, or the angle required for a certain intensity reduction. The complexity can be increased by starting with partially polarised light or by asking for the angle between the first polariser and the plane of polarisation of incident light. Mastery of this concept ensures marks.

Conceptual questions on the nature of light and polarisation methods

high

NEET always includes conceptual questions to test fundamental understanding. Questions like 'Which phenomenon proves the transverse nature of light?' or 'What is the principle behind Polaroid sunglasses?' are perennial favorites. Understanding the distinct characteristics of polarisation by reflection, refraction (double refraction), scattering, and absorption, along with their specific outcomes (e.g., plane of polarisation, O-ray/E-ray), is crucial. These questions assess whether a student has truly grasped the underlying physics rather than just memorizing formulas.

Application of Brewster's Law with Snell's Law

medium

While direct application of $\tan i_p = \mu$ is common, a slightly more challenging variant involves combining Brewster's Law with Snell's Law. For instance, a question might provide the angle of incidence and ask for the angle of refraction at which the reflected light is completely polarised, or vice versa. This requires students to use both $\tan i_p = \mu$ and $i_p + r' = 90^\circ$ (or $\mu_1 \sin i = \mu_2 \sin r$) simultaneously, testing a deeper understanding of light's behavior at interfaces.