Physics · 2026
JEE Main · 23 January 2026, Shift 1 · Q42
Consider light travelling from a medium A to medium B separated by a plane interface. If the light undergoes total internal reflection during its…
Consider light travelling from a medium $\displaystyle A$ to medium $\displaystyle B$ separated by a plane interface. If the light undergoes total internal reflection during its travel from medium $\displaystyle A$ to $\displaystyle B$ and the speed of light in media $\displaystyle A$ and $\displaystyle B$ are $\displaystyle 2.4 \times 10^8 \mathrm{~m} / \mathrm{s}$ and $\displaystyle 2.7 \times 10^8 \mathrm{~m} / \mathrm{s}$, respectively, then the value of critical angle is :
Official answer
From NTA’s final answer key for this paper.
(4)
$\displaystyle \tan ^{-1}\left(\frac{8}{\sqrt{17}}\right)$
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JEE Main 2026 Physics question, with the answer from NTA’s final answer key. Where our answers come from.