A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength $980 \

Question

A hydrogen atom, initially in the ground state is excited by absorbing a photon of wavelength $980 \AA$. The radius of the atom in the excited state, in terms of Bohr radius $a_0$, will be ( $h_c=12500 \mathrm{eV}$-Å )

Professor PC Thomas Classes · Answer

$\Delta E = \frac{12500}{980} \approx 12.75 	ext{ eV}$. This corresponds to transition $n=1 	o n=4$. Radius $r_n = n^2 a_0 \implies r_4 = 16a_0$.