CBSE 2025 · Region 1 · Set 2 · Q9 · 1 mark
A source produces monochromatic light of frequency $\displaystyle 5.0 \times 10^{14} \mathrm{~Hz}$ and the power emitted is $\displaystyle 3.31$ mW. The number of photons emitted per second by the source, on an average is
Official answer
From CBSE’s own marking scheme for this paper.
(A)
$\displaystyle 10^{16}$
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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.