Intensity, frequency, and wavelength

[Ali Polansky 1A]

If intensity doesn't affect electrons being emitted (because in this experiment light doesn't act like a wave), then what has to increase for more electrons to be emitted? I know it's the one-photon one-electron model, but how does the number of photons increase?

[Amina Durrani 3G]

From what I understood in lecture, increasing light intensity increases the number of photons which results in more ejected electrons (if the energy per photon is greater or equal to the energy needed to remove an electron).

[PranaviKolla2B]

The number of photons and intensity are proportional, so I think that if the intensity increases, the number of photons will increase as well.

[JasonLiu_2J]

In the photoelectric experiment, light is acting as a particle in the form of photons. In order for an electron to be emitted, each individual photon must have sufficient energy that is equal to or greater than that required to eject the electron from the surface. If the photons do not have enough energy to match or exceed the required energy to remove the electron, then no electrons will be emitted, no matter how intense the light is. However, if they do have enough energy, then the one photon-one electron relationship will hold true, and the photon will be able to eject the electron. Remember that when light is viewed as a particle, the intensity of the light does not affect the energy of the light, but rather the number of photons of light that are shone onto the surface. If the photons have enough energy to eject the electrons, then increasing the intensity (and thus increasing the number of photons with sufficient energy to eject the electron) will increase the number of electrons ejected (because you have more energy-sufficient protons now). However, if the photons do not have enough energy to eject the electrons, then no electrons will be emitted because you are essentially just increasing the quantity of photons that don't have enough energy to eject the electrons. Hope that makes sense!

[Ali Polansky 1A]

Thank you! So what determines whether the photons have sufficient energy to remove an electron?

[JasonLiu_2J]

When you view light as particles, the factor that influences the energy of the photon is the frequency of the light used. You can see this relationship from the equation E=hv, in which energy and frequency are directly proportional. Thus, as you increase the frequency, the energy of the photon also increases. If the light does not eject electrons, then you must increase the frequency in order to increase the energy of the photons so that the energy of the photons is greater than or equal to the threshold energy (the minimum energy required to eject the electron from the metal surface). Hope this makes the concept a bit clearer!