This simulation illustrates the relationship between the spacing of electron energy levels and the emission spectra of atoms. You see a pair of emission spectra in left below boxes. The above is the spectrum of unknown (hypothetical) atom. Another spectrum corresponds to electron energy levels which are represented in main window. Synchronize both spectra by using floating band controls to set values of electron energy levels. The radio buttons serve to chouse for analyses three level system or four level system. Note, that number of lines (different wavelengths of light) is defined by amount of energy levels and each line shift when the value of electron energy changes.