Quick question about PhotoElectric Effect

AI Thread Summary
When photons in a light beam lack sufficient energy to release tightly bound electrons from a metal, they do not decrease the overall work function of the material. Instead, these photons can still interact with free electrons, increasing their kinetic energy and causing them to move more rapidly within the metal. This increased motion leads to collisions with atoms and other electrons, resulting in energy transfer that heats the metal. Ultimately, the absorbed energy from these photons contributes to warming the surrounding environment. Therefore, while the electrons are not expelled, the energy from the photons still affects the system by increasing thermal energy.
kougou
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Homework Statement


I am wondering, what happens to those photons ( all having same energy level) in a light beam when the photons don't have enough energy to release the electrons in the metal that are more tightly attracted?
Does the overall work function of the material decrease?


Homework Equations



KE= h*f- Workfunction

The Attempt at a Solution



At first glance, the eletrons in the material should become lessly attracted than before because when a light beam shines at an area, the temperature of that area increase.
However, there's a rule that states that frequency below the lowest frequency of the light beam will not release the ANY electron no matter how long you shine the beam. So base on this, the electrons shouldn't become less attracted.

But still, what happen to those electrons that don't have eneough energy to expell the electrons?
 
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kougou said:

Homework Statement


I am wondering, what happens to those photons ( all having same energy level) in a light beam when the photons don't have enough energy to release the electrons in the metal that are more tightly attracted?
Does the overall work function of the material decrease?


Homework Equations



KE= h*f- Workfunction

The Attempt at a Solution



At first glance, the eletrons in the material should become lessly attracted than before because when a light beam shines at an area, the temperature of that area increase.
However, there's a rule that states that frequency below the lowest frequency of the light beam will not release the ANY electron no matter how long you shine the beam. So base on this, the electrons shouldn't become less attracted.

But still, what happen to those electrons that don't have eneough energy to expell the electrons?

When the photon interacts with a free electron , but the energy is not enough to free the electron from the metal, the electron gains kinetic energy, so it will do its random motion inside the metal with higher speed. The electron collides with the vibrating atoms, imperfections or other electrons, and either re-radiates its extra energy as a photon (that is, part of the incident light is reflected) or transfers it to the vibrating atoms or to other electrons, so its extra energy is transferred to the whole metal. The metal becomes a bit warmer, then its transfers heat to the surroundings. So the energy of the absorbed photon will "heat up" the Universe at the end.

ehild
 
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