How much is necessary to increase the internal energy of the He + ion , which is in the ground state , so that it can emit a photon corresponding to the H-a line of the Balmer series ?

( Balmer series ) :  656.3 nm ( red , or H-a ) ,

Calculate the wavelength of the line in the Balmer series corresponding to a transition from  n=4 to n=2 level?

The Balmer series for the hydrogen atom corresponds to electronic transitions that terminate in the state with quantum number n=2 as shown in Figure P28.19. Consider the photon of the longest wavelength corresponding to a transition shown in the figure. Determine (a) its energy and (b) its wavelength. Consider the spectral line of shortest wavelength corresponding to a transition shown in the figure. Find (c) its photon energy and (d) its wavelength, (e) What is the shortest possible wavelength in the Balmer series? 

The Balmer series for the hydrogen atom corresponds to electronic transitions that terminate in the state with quantum number as shown in the figure. Consider the photon of longest wavelength corresponding to a transition shown in the figure. Determine (a) its energy and (b) its wavelength. Consider the spectral line of shortest wavelength corresponding to a transition shown in the figure. Find (c) its photon energy and (d) its wavelength. (e) What is the shortest possible wavelength in the Balmer series?