## College Physics (4th Edition)

$12.75~eV$ of energy must be supplied to the hydrogen atom.
We can find the difference in energy of the hydrogen atom in the ground state and in the state $n=4$: $\Delta E = E_f - E_i$ $\Delta E = \frac{-E_0}{n^2} - (-E_0)$ $\Delta E = \frac{-13.6~eV}{4^2}-(-13.6~eV)$ $\Delta E = 12.75~eV$ $12.75~eV$ of energy must be supplied to the hydrogen atom.