# Calculate the wavelength of an electron moving

Question.

Calculate the wavelength of an electron moving with a velocity of $2.05 \times 10^{7} \mathrm{~ms}^{-1}$.

Solution:

According to de Broglie’s equation

$\lambda=\frac{\mathrm{h}}{m v}$

Where, $\lambda=$ wavelength of moving

particle $m=$ mass of particle $v=$

velocity of particle $\mathrm{h}=$ Planck's

constant

Substituting the values in the expression of $\lambda$ :

$\lambda=\frac{6.626 \times 10^{-34} \mathrm{Js}}{\left(9.10939 \times 10^{-31} \mathrm{~kg}\right)\left(2.05 \times 10^{7} \mathrm{~ms}^{-1}\right)}$

$\lambda=3.548 \times 10^{-11} \mathrm{~m}$

Hence, the wavelength of the electron moving with a velocity of $2.05 \times 10^{7} \mathrm{~ms}^{-1}$ is $3.548$ $\times 10^{-11} \mathrm{~m}$.