Problem 6.62

A narrow stream of electrons with kinetic energy $T$ $=10 \mathrm{keV}$ passes through a polycrystalline aluminium foil, forming a systeun of diffraction fringes on a screen. Calculate the interplanar distance corresponding to the reflection of third order from a certain system of crystal planes if it is responsible for a diffraction ring of diameter $D=3.20 \mathrm{~cm} .$ The distance between the foil and the screen is $l=10.0 \mathrm{~cm}$

\begin{aligned} &\text { 6.62. } d=\pi \hbar k / \sqrt{2 m T} \sin \theta=0.23 \pm 0.04 \mathrm{nm}, \text { where } k=3 \text { and the }\\ &\text { angle } \theta \text { is determined by the formula } \tan 2 \theta=D / 2 l \text { . } \end{aligned}

Wave Properties of particles. Schrodinger Equation.