Q

The absolute refractive index of a medium is always _____.

RRB Group-D; RRB Group-D 24/08/2022 / Shift-II; 03/10/2018 / Shift-I 2022; 2018
✓ Answer: B More than 1
The source selects B for ordinary transparent media in visible light. The wording 'always' is not universal: vacuum has n = 1, and phase indices below 1 occur in some regimes.