Q 12-11-059JEE MainJEE Main 2024 (1 Feb, Shift 2)Easy
Monochromatic light of frequency $6\times10^{14}\ \text{Hz}$ is produced by a laser. The power emitted is $2\times10^{-3}\ \text{W}$. How many photons per second, on average, are emitted by the source? (Given $h = 6.63\times10^{-34}\ \text{J s}$)
Answer: (C) $5\times10^{15}$
$$n = \frac{P}{hf} = \frac{2\times10^{-3}}{6.63\times10^{-34}\times6\times10^{14}} = \frac{2\times10^{-3}}{3.98\times10^{-19}} \approx 5\times10^{15}\ \text{s}^{-1}$$
Solution by Sreeraj P, M.Sc Physics