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When reviewing the photoelectric effect for the midterm I remembered that one of the surprising outcomes of the experiment was that increasing intensity did not make a difference in the removal of electrons. I do understand that what matters is the energy of the photon, I was just wondering what intensity means in this context?
Also, in terms of a wave I believe intensity is equivalent to amplitude of the wave. So if photons were just behaving as a wave then increasing the intensity would mean a larger amplitude and would increase the total energy of the light and excite more electrons. (However this does not happen because light is behaving like a particle).
I feel that what needs to be emphasized is the type of frequency. For example, by increasing the intensity of a photon with a long wavelength may emit little to know electrons. while on the other hand, increasing the intensity of a photon with a short wavelength will mostly like increase the amount of electrons ejected at a 1 to 1 ratio. The matter is the type of frequency used. I hope this helps :)
The reason why increasing the intensity didn't work was because the threshold energy wasn't reached. In order to reach threshold energy, you would need to increase frequency or decrease wavelength, since they are inversely proportional. After the photoelectric effect, they realized that this wasn't a wave model in which increasing intensity would lead to more electrons being ejected.
To add onto the other replies, increasing the intensity/brightness/amplitude of the photons would mean more electrons can be emitted (since there is a 1:1 ratio with one photon ejecting one electron). However, if the threshold energy isn't even reached per photon, an electron would not be emitted. That's why when they kept increasing brightness, nothing happened still. You could have a trillion photons shown onto a metal but no electrons would be emitted if the work function/threshold energy was not reached. The frequency wasn't high enough.
Intensity contributes to the # of electrons removed ONLY if the light source has reached the threshold energy. The overall idea is that increasing intensity of light does not increase the energy of emitted electronics.