Question

An electron and a photon each have a wave length $1$ nm. Find the kinetic energy of electron.

Answer 1

Wavelength$=1\ast {10}^{-9}m$

Plancks constant,$h=6.63\ast {10}^{-34}Js$

$Kineticenergy.K=\frac{1}{2}\ast \frac{p^2}{m}$

$m=9.1\ast {10}^{-31}kg$

$p=6.6\ast {10}^{-25}kgm{s}^{-1}$

$K=\frac{1}{2}\ast \frac{{(6.63\ast {10}^{-25})}^2}{9.1\ast {10}^{-31}}=2.415\ast {10}^{-19}J$

$K=\frac{2.415\ast {10}^{-19}}{1.6\ast {10}^{-19}}=1.51eV$