In this study, measurements of the light curve were taken to assess photosynthetic competence in Vaucheria algae. The Chl a fluorescence of photosystem II (PSII) was measured using a pulse amplitude modulated fluorometer. The maximum quantum yield (Fv/Fm) and electron transport rates (ETR) were determined in dark-adapted samples. The light curves were measured by varying the light intensity in 10 steps and recording the effective quantum yield. The data were then analysed using a model known as the photosynthetic light response curve, which describes the relationship between ETR and light intensity. The model assumes that ETR increases linearly with light intensity at low levels, but then slows down and approaches a maximum value (ETRmax) at higher light intensities. The half-saturation constant (k) represents the light intensity at which the ETR is half its maximum. These parameters, ETRmax and k, play a crucial role in understanding the photosynthetic properties of algae under different light conditions. The data were analysed using nonlinear least squares estimates of the parameters in R Studio.