Show that the energy of first excited state of `He^(+)` atom is equal to the energy of electron in the first orbit of hydrogen atom.

Explanation

`E_n=(mZ^2e^4)/(2n^2h^2)`
`therefore (E_1)/(E_2)=((Z_1)/(Z_2))^2*((n^2)/(n^1))^2=(2/1)^2xx(1/2)^2=1 or, E_1=E_2`