Intensity

[Rithwik Narendra 2H]

Consider the following statement: "A bright light always causes more electrons to be emitted than a faint light"

Is this true?

I believe it is false. In class, we learned that intensity is proportional to number of electrons emitted. However, this is only if the threshold established by the work function reached. In the case where the threshold is not reached, the number of electrons emitted would be 0. Therefore a bright light does not ALWAYS cause more electrons to be emitted, as there is one case where the number would be equal.

Am I missing something here?

[Janis 3B]

In terms of photons, higher amplitude light means more photons hitting the metal surface. This results in more electrons ejected over a given time period. However, I think the most important aspect is the frequency of the light, which must be high enough to eject photons from the metal surface. Therefore, you are correct, at least in my opinion, that the statement is only true if that threshold frequency has already been reached.

[Ingrid 14A_2E]

light intensity refers to the number of photons that we have, therefore a greater intensity (this is assuming the energy per photon meets or surpasses the threshold energy) would lead to more electrons being ejected over a given time period (ratio of 1 photon: 1 electron), otherwise increasing the intensity of a light with energy per photon under threshold only leads to more photons being present (and no electron ejections).


Hope this helps!