Photoelectric effect with high frequency and low intensity of light What happens to the number of photons striking the free electrons on metal surface with high frequency and low intensity of light? High and low intensity of light of photons to electron on metal surface
 A: A puzzling effect of this phenomenon as was first discovered by Lenard in 1902, was that the maximum kinetic energy (velocity) of the emitted electrons was independent of of the intensity of the incident light but proportional to the frequency (wavelength).
A: I think what you are trying to talk about is the photo-electric effect. It basically says, that when photons of a certain frequency strike the surface of a conductor, electrons are emitted.
However, this happens only for certain frequencies. You should recall $E=hf$, where $E$ is energy and $f$ is the frequency of the photon. The metal tries to 'hold' the electron with a certain energy, so the incident photon must have an energy higher than this 'binding' energy commonly called the work function of the surface.
We have : $hf - W = \frac{1}{2}mv^2$
The term $W$ is the work function and the last term is the kinetic energy of the electron. See that if the frequency is not more than the work function, the kinetic energy is negative, which is non-sensical.
In this form, the intensity is meaningless, as the kinetic energy depends on frequency alone. This is also evidence for the particle nature of life.
However, let us change the set up a bit. We have two wires, in a test tube, and the ends are not connected. We shine light over one of these wires, and connect the circuit on the other end. We also use a galvanometer to measure the current. The logic is, if the photoelectric effect is true, then the electrons from the end of one wire should reach the end of the other, and thus current must flow. This current can be detected in the galvanometer.
If you increase the intensity of light, it means more photons are hitting the surface, and if they have a high enough energy, more electrons are being emitted. So, if more electrons are emitted, our final saturation current should be more. So, if you increase the intensity, the galvanometer will give you a higher current reading in the end. However, remember, there will be a time when all the released electrons reach the other side, and the current will become constant, and this is called the saturation current.
Higher frequency means you'll reach this saturation much earlier.
Hope this helps.
