Question

A moving electron his $4.55\times {10}^{-25}$ joules of kinetic energy. Calculate its wavelength. [miss e, $9.1\times {10}^{31}$ kg and $h=6.626\times {10}^{-34}$ kg $m^2{s}^{-1}$].

Answer 1

Kinetic energy $\frac{1}{2}m{v}^2=4.55\times {10}^{-25}J$
$m=9.1\times {10}^{-31}Kg$
$h=6.626\times {10}^{-34}Kg{m}^2{s}^{-1}$
$\frac{1}{2}\times (9.1\times {10}^{-31})v^2=4.55\times {10}^{25}$ (or)
$v^2=\frac{4.55\times {10}^{-25}\times 2}{9.1\times {10}^{-31}}={10}^6$
$v={10}^{3}mse{c}^{-1}$
$\lambda =\frac{h}{mv}\frac{6.626\times {10}^{-34}}{(9.1\times {10}^{-33})\times {10}^3}=7.5\times {10}^{-7}m$
$\lambda =7.25\times {10}^{-7}m$