JEE Main 2008 — Dual Nature of Matter Question with Solution

Paragraph: Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see in figure).
Question: Electrons accelerated by potential $V$ are diffracted from a crystal. If $d=1\mathring{A}$ and $i=30^{\circ },V$ should be about $\left(\mathrm{h}=6.6\times 10^{-34}\mathrm{Js},{\mathrm{m}}_{\mathrm{e}}=9.1\times 10^{-31}\mathrm{kg},\mathrm{e}=1.6\times 10^{-19}\mathrm{C}\right)$