DISCLAIMER: I have not yet fully entered into the vast field of quantum mechanics and and was reading about the photoelectric effect as a part of chemistry, however I feel, the topic of structure of atom formally comes under physics so I will put forward my question over here. Please answer the question in the most rudimentary way as possible. Although I have completed sufficient amount of classical mechanics and electromagnetism to be able to understand certain terminologies so feel free to include that.
DISCLAIMER 2.0 (edit): the question which is linked is, whether or not the number of photoelectrons increase on increasing frequency.. My question is how does the change in frequency affect the photocurrent. (this was to differentiate the questions) In photoelectric effect experiment, why will the number of photoelectrons not change on increasing frequency?
MAIN QUESTION: Why doesn't the frequency affect the photocurrent? I understand that photointensity effects the photocurrent as number of photons striking in a unit area in unit time is increased, hence number of charged particles increased and hence, current flow increased.
I also understand the fact that changing the frequency will only change the energy of the emitted electron and not the number of electrons. But my argument is, as the energy has been increased, so has the velocity, which suggests in unit time, more charged particles will flow. Shouldn't that increase the current flow? As per what I understand kinetic energy of particle increases then stopping potential too increases; current should also increase. Any help would be appreciated.
Best Answer
It does affect it, in general. It just does not affect the number of ejected photoelectrons (to zeroth order).
If you google for the emission spectrum of your favorite metal, you will see that the emitted intensity does indeed change with incident frequency. This is because the "optical constants" of a material are not really "constant." They change with frequency. But we ignore this in the elementary discussion of the photoelectric effect for various reasons, some explained below.
If you were able to measure the current in such a way that the ejected electron velocity matters, then yes.
But in a typical elementary photoelectric effect experiment, you collect the electrons into a collector apparatus that is very blunt. It's slurping up whatever electrons get kicked out of the material and is not really sensitive to their individual (or average) speeds. It is basically counting the number of electrons that are ejected in a given time, not how long it takes for those electrons to get from the material to the collector.
In addition, I think the point of the elementary discussion of the photoelectric effect is that if a single photon has enough energy to kick out a single electron, then increasing the frequency doesn't change that--i.e., a single electron still gets kicked out of the material by a single photon. (Caveat: There are higher order processes that could provide small corrections to this effect.)