
Methods such as chlorophyll fluorescence, the amount of O2 emitted or the amount of CO2 assimilated are commonly used to estimate the photosynthetic activity of plants, but none of these methods shows us directly the electrical activity that occurs during photosynthesis. The purpose of this study is to show that the photosynthetic activity can be obtained from the behavior of the electrical resistance of extra chlorophyll space. The model used in this study is that of Cole. It appears from our analysis that there is a distinct relationship between the behavior of the extra chlorophyll space resistance and the amount of O2 emitted or the amount of CO2 assimilated according to the intensity of the light; while the amount of O2 emitted or the amount of CO2 assimilated increases according to the intensity of the light up to a certain threshold, the extra chlorophyll space resistance decreases according to the intensity of white, blue, yellow and red light until it reaches a certain threshold. However, the green light is found to be inactive.