Question

Write briefly the underlying principle used in Davison - germer experiment to verify wave nature of electron experimentally. What is the de- Broglie wavelength of an electron with kinetic energy (K.E) 120 eV?

Answer 1

Hi..
fine beam of accelerated electrons obtained from the electron gun is made to fall normally on the surface of a nickel crystal.
The incident electrons are scattered in different direction by the atoms of the crystal. The intensity of the scattered beam is measured for different values of scattering angle ϕ , the angle between the incident and the scattered electron beam .
(b) Kinetic energy of the electron =12mv2
12mv2=120ev
=120×1.6×10−19J
mv2=240×1.6×10−19
m2v2=9.11×10−31×240×1.6×10−19
mv=9.11×240×1.6×10−50−−−−−−−−−−−−−−−−−−−√
λ=hmv=6.6×10−349.11×240×1.6×10−50−−−−−−−−−−−−−−−−−√
=1.115×10−10m
=1.115∘A...


Hope this helps u!!!

Answer 2

Answer:

Diffraction effects are observed for beams of electrons scattered by the crystals.

λ=1.227nm /√V

λ=1.227nm/√120

Value of  λ = 0.112nm

it can also be done by using the formula

λ = h/√2meV