A `12.5eV` electron beam is used to bombard gaseous hydrogen at room temperature. What serious of wavelength will be emitted?

Explanation

In ground state, energy of gaseous hydrogen at room temparature `= -13.6 eV`, when it is bombarded with 12.5 eV electron beam, the energy becomes `13.6 + 12.5 = -1.1 eV`
The electron would jump from n 1 to n=3 where `E_(3)=(-13.6)/(32)=-1.5 eV`
On de-excitation the electron may jump from n=3 to n=2 giving raise to Balmer series. it may also jump from n=3 to n=1 giving rise to Lyman series.