Question

de Broglie wavelength of a 1.4 keV electron?

___ nm

Answer 1

Answer: The de broglie wavelength of a particle of mass m is given by

Where p is the momentum of the particle.

Also the relation between the kinetic energy and momentum of a particle is given by

Therefore the de broglie wavelength of the electron becomes

Substituting the given value of energy

E = 1.4 KeV = 1.4 * 10^(3) eV

As 1eV = 1.6 × 10^(-19) joules

Therefore, E = 1.4 * 10^(3) * 1.6 * 10^(-19) joules

and mass of electron, m = 9.11 *10^(-31) kg

and planks constant, h = 6.626 * 10^(-34) js

We get,

Or

Which is the required de-broglie wavelength of the electron