Q. The ratio of the energy of a photon with $\lambda = 150$ nm to that with $\lambda = 300$ nm is

A) 2
B) $\frac{1}{4}$
C) 4
D) $\frac{1}{2}$
Explanation

(a) According to Einstein, the energy of photon is given by
$E = hv = \frac{hc}{\lambda}$
Where $h$ is Planck’s constant, $c$ the speed of light and $\lambda\ the\ wavelength.$
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{E_{1}}{E_{2}} = \frac{\lambda_{2}}{\lambda_{1}}$
Given, $\lambda_{1} = 150\ nm\ ,\ \lambda = 300$nm
$\therefore\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{E_{1}}{E_{2}} = \frac{300}{150} = \frac{2}{1}\ $

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

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