Dispersion of Light — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Dispersion of Light.

Comparative Dispersive Power of Materials

high

NEET often tests the understanding of material properties. A question comparing the dispersive power of two different materials, given their refractive indices for various colors, is highly probable. This tests not just formula application but also the conceptual understanding that dispersive power is a material characteristic, independent of prism geometry. Students might be asked to identify which material is 'more dispersive' or to calculate and compare values, often with similar $(n_V - n_R)$ values but different $(n_Y - 1)$ values to act as a trap.

Dispersion in Combination with Achromatic Prisms/Lenses

medium

A slightly more advanced application of dispersion is the concept of achromatic combinations (prisms or lenses) where two different materials are used to achieve dispersion without deviation, or deviation without dispersion. While full derivations might be beyond NEET scope, conceptual questions about the conditions for such combinations (e.g., $\omega_1/\omega_2 = -A_2/A_1$ for dispersion without deviation) or identifying the purpose of such combinations (to eliminate chromatic aberration) are possible. This tests a deeper understanding of how dispersion is managed in optical instruments.

Graphical Representation of Refractive Index vs. Wavelength

low

While less common, a question might present a graph showing the variation of refractive index with wavelength for different materials and ask to infer which material has higher dispersive power or which color deviates most. This tests the ability to interpret graphical data in the context of dispersion, linking the visual representation to Cauchy's formula and the concept of wavelength-dependent refractive index. It would be a good way to test conceptual understanding in a novel format.