If de broglie wavelength of electron in the ground state of hydrogen atom is λ, what is the de Broglie wavelength of electron in the first excited state of He+  ion  ?

(3)For a hydrogen - like ion, speed of electron V=V0.Zn  where  V0 is the speed of electron in the ground state of H - atom.∴  de  broglie  wavelength  =hmv =hmV0.nz∴  λ  =hmv011  and  λ' =hmV0.22=hmV0∴   λ'=λ