Mechanics of the photoelectric effect

In summary, When the frequency of the shining light source is increased in an experiment of the photoelectric effect, the number of ejected electrons from the metal surface decreases due to the higher energy of the photons, which results in a need for fewer photons to maintain the same intensity. This can cause confusion as it may seem counterintuitive, but it is due to the inverse relationship between frequency and wavelength. Additionally, the increased final voltage can also prevent additional electrons from being ejected.
  • #1
D.Freya
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Given an experiment of the photoelectric effect, if we keep the intensity of the shining light source constant, by increasing the frequency of the light, the number of ejected electrons from the metal surface "decreases". I understand that increasing frequency (assuming it is already higher than the threshold) will eject electrons at higher kinetic energies, thus resulting in a higher final voltage. But I am confused as to why the number of ejected electrons decreases with higher frequencies?? I don't see the relationship.

Side note: I thought about how wavelength is inversely proportional to frequency and so higher frequency --> lower wavelength and the possibility of a photon impacting an electron decreases. I also thought about how the the increased final voltage would build up faster, preventing additional electrons from being ejected. Both answers are apparently incorrect.
 
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  • #2
Higher frequency photons have more energy, so in order to keep the intensity (power) the same you have to have fewer of these higher energy photons.
 
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FAQ: Mechanics of the photoelectric effect

1. What is the photoelectric effect?

The photoelectric effect is a phenomenon in which light (or other electromagnetic radiation) causes the emission of electrons from a material. This effect was first observed by Heinrich Hertz in 1887 and was later explained by Albert Einstein in 1905, for which he received the Nobel Prize in Physics in 1921.

2. How does the photoelectric effect work?

The photoelectric effect occurs when a photon of light interacts with an atom in a material, causing an electron to be ejected from the atom. This requires that the photon has enough energy to overcome the binding energy of the electron to the atom. The ejected electrons are called photoelectrons and the remaining atom is left with a positive charge.

3. What is the significance of the photoelectric effect?

The photoelectric effect is significant because it provided evidence for the particle nature of light and helped to develop the theory of quantum mechanics. It also has practical applications in technologies such as solar cells and photomultiplier tubes.

4. How is the photoelectric effect related to the work function?

The work function is the minimum amount of energy required to remove an electron from the surface of a material. In the photoelectric effect, the energy of the incident photon must be greater than or equal to the work function in order for electrons to be emitted. If the energy of the photon is less than the work function, no electrons will be emitted.

5. What factors affect the photoelectric effect?

The photoelectric effect is affected by several factors, including the intensity and frequency of the incident light, the work function of the material, and the number and energy levels of electrons in the material. It is also influenced by the composition and structure of the material, as well as external factors such as temperature and electric fields.

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