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I'm going to have to remember this point, because our teachers are convinced that it should be increasing intensity = increased emf (i think it was A).Originally posted by wogboy
Actually the emf produced by the photoelectric effect is independent of the intesity of the light. It just depends on the frequency of the light.
So then you might ask what happens when you increase the intensity of the incoming light (but not its frequency). Only the current increases, but the emf isn't affected. This is because even if you increase the intensity, the energy per unit charge is still the same (each electron still receives the same amount of energy), so the emf is unchanged (emf = energy/charge). It's just there will be more electrons that will be ejected, so the current will increase.
So I believe the correct answer for the multiple choice question is increasing the frequency (not intensity) causes a increased emf.
Damn! Another mark down the drain for not reading the q correctly.Originally posted by wogboy
Actually the emf produced by the photoelectric effect is independent of the intesity of the light. It just depends on the frequency of the light.
So then you might ask what happens when you increase the intensity of the incoming light (but not its frequency). Only the current increases, but the emf isn't affected. This is because even if you increase the intensity, the energy per unit charge is still the same (each electron still receives the same amount of energy), so the emf is unchanged (emf = energy/charge). It's just there will be more electrons that will be ejected, so the current will increase.
So I believe the correct answer for the multiple choice question is increasing the frequency (not intensity) causes a increased emf.