The kinetics of fluorescence emission by chlorophyll is of great interest not only for research purposes, but also for teaching the operation of photosynthesis and its alteration by stress factors, since it informs about the state of photochemical reactions. Under optimal conditions of the photosynthetic apparatus, the energy captured by the chlorophylls is invested, with great efficiency, in the primary photochemical reactions of photosynthesis (more than 90%) and very little is dissipated in the form of fluorescence. Therefore, an increase in fluorescence emission compared to the basal level always implies an alteration in the photosynthetic process.