# where do we use the formula Eev/atom(which is =12400)...give me an example...

The equation is an analogous derived for the computation of energy of photons, if photon energy is given then the expression is used in computing its wavelength. The expression and example are expressed below,

${\lambda}_{\lambda}=\frac{12398}{{E}_{eV}}=\frac{12400}{{E}_{eV}}\to photons\phantom{\rule{0ex}{0ex}}forexampleifE\hspace{0.17em}=10MeVthenitsdeBrogliewavelengthis,\phantom{\rule{0ex}{0ex}}{\lambda}_{\lambda}=\frac{12400}{10\times {10}^{6}}=1240\mu m$

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