Q 12-11-069JEE MainJEE Main 2024 (29 Jan, Shift 2)Easy
Two sources of light emit with a power of $200\ \text{W}$. The ratio of number of photons of visible light emitted by each source having wavelengths $300\ \text{nm}$ and $500\ \text{nm}$ respectively, will be:
Answer: (D) $3:5$
Number of photons per second $N = \dfrac{P}{hc/\lambda} = \dfrac{P\lambda}{hc}$, so for equal power $N \propto \lambda$:
$$\frac{N_1}{N_2} = \frac{300}{500} = \frac35$$
Solution by Sreeraj P, M.Sc Physics