For which pair among the following, the refractive index will have the minimum and maximum value, respectively?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Vacuum, diamond
The refractive index of a medium is \( n = c/v \). Light travels fastest in vacuum, so vacuum has the least possible value, \( n = 1 \); every material medium has \( n \gt 1 \).
The typical values of the media named in the options are
\( \text{vacuum } 1 \lt \text{air } 1.0003 \lt \text{water } 1.33 \lt \text{crown glass } 1.52 \lt \text{dense flint glass } 1.62 \lt \text{diamond } 2.42 \)
So the minimum belongs to vacuum and the maximum to diamond, which has one of the highest refractive indices of all transparent materials.
NCERT (2026-27):
Total Internal Reflection – …
