Question

According to Bohr's theory, the electronic energy of hydrogen atom in the n^th  Bohr's orbit is given by :

Calculate the longest wavelength of electron from the third  Bohr's orbit of the He⁺ ion.

Answer 1

Energy of H-like atom E = E₁ x Z²

where E = Energy of H like atom, ie, He⁺ion

E₁ = Energy of H-atom

Z = Atomic number of H-like atom

To have longest wavelength, the transition would be from r=3 to n = 4,hence