(a)[2]
Show that the momentum $p$ of the electron after acceleration is given by $p = \sqrt{2mqV}$.
(b(i))[2]
The potential difference $V$ used to accelerate the electron is $120\,\text{V}$. State what the de Broglie wavelength means.
(b(ii))[3]
Calculate the de Broglie wavelength for the electron.
(c)[2]
The spacing between copper atoms in a copper crystal is about $2 \times 10^{-10}\,\text{m}$. Using your answer to (b)(ii), suggest whether electron diffraction could be seen with a beam of electrons accelerated through a potential difference of $120\,\text{V}$ and then directed at a thin copper crystal.