An electron (of mass $m$ ) and a photon have the same energy $E$ in the range of a few $\mathrm{e}\mathrm{V}$. The ratio of the de-Broglie wavelength associated with the electron and the wavelength of the photon is ( $\mathrm{c}=$ speed of light in vacuum)

• A

  $\frac{1}{c}{\left(\frac{2E}{m}\right)}^{1/2}$
• B

  $c{\left(2mE\right)}^{1/2}$
• Correct answer
  C

  $\frac{1}{c}{\left(\frac{E}{2m}\right)}^{1/2}$
• D

  ${\left(\frac{E}{2m}\right)}^{1/2}$

Hence, the correct answer is option: 'C'.