Q 12-11-005NEETNEET 2025Top questionMedium
A photon and an electron (mass $m$) have the same energy $E$. The ratio ($\lambda_{\text{photon}}/\lambda_{\text{electron}}$) of their de Broglie wavelengths is: ($c$ is the speed of light)
Answer: (C) $c\sqrt{\dfrac{2m}{E}}$
Concept. Photon $\lambda = \dfrac{hc}{E}$; electron $\lambda = \dfrac{h}{\sqrt{2mE}}$.
Step 1. Ratio.
$$\frac{\lambda_{\text{photon}}}{\lambda_{\text{electron}}} = \frac{c\sqrt{2mE}}{E} = c\sqrt{\frac{2m}{E}}$$
Answer. $c\sqrt{\dfrac{2m}{E}}$ (Option C).
Solution by Sreeraj P, M.Sc Physics