If the de Broglie wave length of electron in the ground state of hydrogen atom is λ, Then the de Broglie wave length in the third excited state of He+ ion is

If v0 be the speed of electron in the ground state of Hydrogen atom, then λ=hmv0Now, vn  = speed of electron in the nth energy level of a Hydrogen like ion =v0zn∴λn=hmvn=hmv0zn=nz.hmv0=42λ=2λ