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Hi Alvaro Chumpitaz 4D! I respectfully disagree with ishaa Diwakar 4E and the comment that "the electron would not be ejected from the metal". If the Energy of the photon of incoming light is EQUAL to the work function (Energy THRESHOLD) then the ELECTRON WILL BE EJECTED. This is true because of the data gathered in the photoelectric experiment. In the experimental design, the detector that notes whether electrons are ejected from the metal has a positive charge to it which will attract the ejected electrons EVEN IF there is NO KINETIC ENERGY. Energy THRESHOLD (work function) is the MINIMUM energy required to EJECT the electron. So, the electron WILL BE EJECTED if E-photon = E-threshold.
The key observation in worked out photoelectric effect problems is that when an ejected electron has 0 kinetic energy, the energy of the photon is equal to the energy required to remove the electron. The example in lecture based off this premise asked what could be the longest wavelength light to accomplish this and the threshold energy value is used for the "E" in the equation.
In the photoelectric effect, if the energy of the photon is equal to that of the work function (i.e. no kinetic energy), what would happen is that the energy threshold will be met and the electron will be ejected.
Alvaro Chumpitaz 4D wrote:So in the photoelectric effect, what would happen if the energy of the photon is equal to that of the work function (ie no KINETIC ENERGY)?
No additional kinetic energy means that the only output from the metal is the ejected photon. There is no additional kinetic energy resulting from the light source hitting the solid metal.
When the energy of the photon is exactly equal to the work function, the kinetic energy is 0, so the electron will still be ejected, but it won't be able to escape from the nucleus because the velocity is 0. Usually, if the energy of the photon is greater than the work function, the electron is ejected with some velocity.
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