Q. A source $S_{1}$ is producing $10^{15}$ photons per second of wavelength $5000\mathring{\mathrm{A}}.$ Another source $S_{2}$ is producing $1.02 \times 10^{15}$ photons per second of wavelength $5100\mathring{\mathrm{A}}.$ Then (power of $S_{2}$)/(power of $S_{1}$) is equal to

A) 0.98
B) 1.00
C) 1.02
D) 1.04
Explanation

(b) $\frac{Power\ of\ S_{2}}{Power\ of\ S_{1}} = \frac{n_{2}\left( \frac{hc}{\lambda_{2}} \right)}{n_{1}\left( \frac{hc}{\lambda_{1}} \right)} = \frac{n_{2}\lambda_{1}}{n_{1}\lambda_{2}} = 1$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.