Find the kinetic energy of an electron whose de broglie wavelength is 34.0 nm.

The De Broglie wavelength of the electron is

And we can use De Broglie's relationship to find its momentum:


Given , with m being the electron mass and v its velocity, we can find the electron's velocity:


This velocity is quite small compared to the speed of light, so the electron is non-relativistic and we can find its kinetic energy by using the non-relativistic formula: