Physics - Modern Physics Question with Solution | TestHub

$E=E_4-E_1=-\frac{13.6}{4^2}—\left(-\frac{13.6}{1^2}\right)$

$=-0.85+13.6=12.75\mathrm{ }\mathrm{e}\mathrm{V}$

$=12.75\times 1.6\times {10}^{-19}\mathrm{ }\mathrm{J}$

$P=\frac{E}{c}=\frac{12.75\times 1.6\times {10}^{-19}}{3\times {10}^8}$

$=6.8\times {10}^{-\mathrm{27 }}\mathrm{k}\mathrm{g-}\mathrm{m }{\mathrm{s}}^{-1}$

This must be the momentum of recoiled hydrogen atom (in opposite direction)