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Physics · PYQ NEET UG 2025

हिन्दी

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)

  1. \( \frac{E}{c\sqrt{2m}} \)
  2. \( c\sqrt{2mE} \)
  3. \( c \sqrt{\frac{2m}{E}} \)
  4. \( \frac{1}{c} \sqrt{\frac{E}{2m}} \)

Correct answer · Option 3

\( c \sqrt{\frac{2m}{E}} \)

Explanation

For photon, \( \lambda_{\text{photon}} = \frac{hc}{E} \). For electron, \( \lambda_{\text{electron}} = \frac{h}{\sqrt{2mE}} \). Dividing them gives \( \frac{\lambda_{\text{photon}}}{\lambda_{\text{electron}}} = \frac{hc}{E} \frac{\sqrt{2mE}}{h} = c \sqrt{\frac{2m}{E}} \).

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