For the principle of conservation of energy, the increase in kinetic energy of the atom is equal to the energy lost when moving through the potential difference:
[tex]\Delta K=\Delta U=q \Delta V[/tex]
where q is the charge of the Beryllium atom:
[tex]q=4 e=4 \cdot (1.6 \cdot 10^{-19}C)=6.4 \cdot 10^{-19}C[/tex]
and [tex]\Delta V=6.0 V[/tex]. Therefore, the increase in kinetic energy is
[tex]\Delta K = (6.4 \cdot 10^{-19}C)(6.0 V)=3.8\cdot 10^{-18} J[/tex]
