Question:medium

A photon and an electron have the same energy \( E \). If \( \lambda_p \) is the wavelength of the photon and \( \lambda_e \) is the de Broglie wavelength of the electron, then the ratio \( \frac{\lambda_p}{\lambda_e} \) is:

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Use the relations \( E = \frac{hc}{\lambda_p} \) for photons and \( \lambda_e = \frac{h}{\sqrt{2mE}} \) for electrons to find the wavelength ratio.
Updated On: Nov 26, 2025
  • \( \frac{E}{mc^2} \)
  • \( \frac{\sqrt{2mE}}{c^2} \)
  • \( \frac{\sqrt{2mE}}{c} \)
  • \( \frac{\sqrt{2mE}}{R} \)
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The Correct Option is C

Solution and Explanation

The energy of a photon is related to its wavelength by the equation: \[ E = \frac{hc}{\lambda_p} \] Where: - \( h \) represents Planck's constant. - \( c \) is the speed of light. - \( \lambda_p \) denotes the photon's wavelength. For an electron, the de Broglie wavelength is expressed as: \[ \lambda_e = \frac{h}{\sqrt{2mE}} \] Where: - \( m \) signifies the mass of the electron. - \( E \) is the electron's energy. The ratio of these wavelengths is calculated as follows: \[ \frac{\lambda_p}{\lambda_e} = \frac{\frac{hc}{E}}{\frac{h}{\sqrt{2mE}}} = \frac{c}{\sqrt{2mE}} \] Consequently, the wavelength ratio is: \[ \frac{\lambda_p}{\lambda_e} = \frac{\sqrt{2mE}}{c} \]
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