From the post https://www.physicsforums.com/threads/photoelectric-effect-saturation-current.720506/ and http://www.thephysicsforum.com/quantum-physics/3921-photoelectric-current-dependence-potential-difference.html [Broken] I have some idea on why does a higher potential different will not increase the saturation current. What I understand is that there are a "upper limit of photoelectron produced", although the photoelectrons moved faster towards anode under higher potential difference, but the number of photoelectrons arrived anode PER SECOND is still a constant. Am I wrong with this idea? If not, then, consider the case: I have a sensitive, ideal ammeter, that can record current in the circuit every single unit of time. Then, I fixed the frequency and intensity of the illuminating radiation on cathode(that always higher then threshold frequency), then slowly increase the potential different even after reached the saturation current. Say, we obtained the saturation current, 1A once the potential difference is 5V. Will I get the reading like, example, at 500V, the current is 100A in a instant then continuously decreased for a while, where giving me the mean current in 1s = 1A ? Because I am still thinking that the drift velocity of the photoelectron will affect the current. Sorry if I cannot state my problem clearly due to poor command on english. Thanks in advance.