CBSE 2025 · Region 1 · Set 3 · Q8 · 1 mark
A point source is placed at the bottom of a tank containing a transparent liquid (refractive index $\displaystyle n$ ) to a depth H . The area of the surface of the liquid through which light from the source can emerge out is
Official answer
From CBSE’s own marking scheme for this paper.
(B)
$\displaystyle \frac{\pi \mathrm{H}^{2}}{\left(n^{2}-1\right)}$
Ray Optics and Optical InstrumentsRefraction at Spherical Surfaces and by LensesApplymcqmedium
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CBSE Class 12 Physics past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.