This is an image of the energy levels of a hydrogen atom. At the bottom of the image is a horizontal line indicated as E(1). A vertical arrow pointing upwards is labelled as increasing energy. 7 energy levels, E(2) to E(7) inclusive, are labelled with horizontal lines becoming increasingly more bunched up as the energy increases in the vertical direction. After E(7) subsequent energy levels are shown as a thick line. Two way arrows are drawn indicating energy transitions between energy levels; between E(2) and E(3) this is shown as 1.89 eV; between E(2) and E(7) this is shown as 3.12 eV.