Question

Find the lowest energy of an electron confined in a cubical box of each side 1 Å?

Answer 1

$E=\frac{h^2}{8ma^2},$

$E=\frac{(6.63\cdot 10^{-34})^2}{2\cdot 9.11\cdot 10^{-31}\cdot 10^{-20}}\approx24.12\cdot 10^{-18} ~\text{J}=24.12~\text{aJ}.$