Speed of EM Waves — Predicted 2026

AI-Predicted Question Angles for UPSC 2026

Based on trend analysis, current affairs, and recurring themes in Speed of EM Waves.

Calculation of speed in a medium given relative permittivity/permeability

high

This is a direct application of the core formula $v = c/\sqrt{\mu_r \epsilon_r}$. It tests both formula recall and basic arithmetic. Given that $\mu_r$ is often 1 for dielectrics, it simplifies to $v = c/\sqrt{\epsilon_r}$, making it a straightforward calculation that NEET frequently assesses. Students need to be careful with square roots and powers of ten.

Conceptual questions on the constancy of speed in vacuum vs. variability in medium

high

NEET often includes conceptual questions to check fundamental understanding. Questions might ask which statement about EM wave speed is correct/incorrect, focusing on the independence of speed from frequency in vacuum, its dependence on medium properties, and the fact that $v < c$. These questions assess whether students have grasped the core principles beyond just memorizing formulas.

Problems combining speed, wavelength, and frequency across different media

medium

These problems require multiple steps: calculating speed in a medium, then using the wave equation ($v = f\lambda$) while remembering that frequency ($f$) remains constant. This tests a deeper understanding of wave properties and is a common way to create slightly more challenging numerical problems. Students often make mistakes by assuming wavelength or frequency remains constant when it shouldn't.