The ground state energy of hydrogen atom is – 13.6 eV. If an electron makes a transition from an energy level – 0.85 eV to –3.4 eV, calculate the wavelength of the spectral line emitted. To which series of hydrogen spectrum does this wavelength belong?

Using the formula,

For, n=1; E₁ = - 13.6 eV

During the electron transmission, E_A = - 0.85 eV to E_B = -3.4 eV

So, from equation (i), we have

 

Therefore, electron transition takes place from n=4 to n=2 which corresponds to Balmer series.

We know,

Here, 

n_A = 4 ; n_B = 2 ; R = 1.097 x 10⁷ m^-1

Then,