Page "Energy level" Paragraph 36

An increase in energy level from E < sub > 1 </ sub > to E < sub > 2 </ sub > resulting from absorption of a photon represented by the red squiggly arrow, and whose energy = Planck's constant | h Frequency | νA decrease in energy level from E < sub > 2 </ sub > to E < sub > 1 </ sub > resulting in emission of a photon represented by the red squiggly arrow, and whose energy = Planck's constant | h Frequency | ν