What were the real results of the photoelectric effect experiment?

In summary: This is actually wrong, as the binding energy of the electrons in the cathode is actually the binding energy of the anode. By modifying the work function, one can change the amount of emitted electrons.
  • #1
pkc111
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TL;DR Summary
I am confused about information regarding the effect of light frequency on photocurrent in the Lenard's apparatus.
Pearson Physics 12 states:
"When the light sources have the same intensity but different frequencies, they produce the same maximum current"

However, Phet Simulation Photoelectric Effect seems to show that photocurrent changes with light frequency (eg see below for different photocurrents at 179 nm and 414 nm incident light wavelengths on sodium:

1654308153203.png

1654308178294.png
 
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  • #3
jedishrfu said:
Khan Academy has a good description of the experiment and results found

https://www.khanacademy.org/science/physics/quantum-physics/photons/a/photoelectric-effect
Hmmm. That page doesn't appear to be in line with the PhET simulation, as it says that the electric current is proportional to the intensity of the light, not the frequency, whereas the PhET simulation has current increase as both intensity and frequency increase.
 
  • #5
Ironically in almost all treatments in physics books (even at the university level) in
$$\hbar \omega=E_{\text{kin}}+W_B$$
for the famous experiment by Millikan with the stopping voltage the constant ##W_B## is quoted wrongly as the binding energy of the electrons in the cathode, rather it's the binding energy of the anode [1]. To establish this, by the way, took Millikan years, while the measurement of Plancks constant ##h=2 \pi \hbar## was pretty right from the very beginning.

[1] J. Rudnick, D. Tannhauser, Concerning a widespread error in the description of the photoelectric
effect, Am. J. Phys. 44, 796 (1976).
https://doi.org/10.1119/1.10130
 
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  • #6
vanhees71 said:
Ironically in almost all treatments in physics books (even at the university level) in
$$\hbar \omega=E_{\text{kin}}+W_B$$
for the famous experiment by Millikan with the stopping voltage the constant ##W_B## is quoted wrongly as the binding energy of the electrons in the cathode, rather it's the binding energy of the anode [1]. To establish this, by the way, took Millikan years, while the measurement of Plancks constant ##h=2 \pi \hbar## was pretty right from the very beginning.

[1] J. Rudnick, D. Tannhauser, Concerning a widespread error in the description of the photoelectric
effect, Am. J. Phys. 44, 796 (1976).
https://doi.org/10.1119/1.10130

Actually, even that is not as clear-cut.

The nature of what a "work function" is is more complicated than such a simple answer. For example, in many instances, it is treated as simply the image charge potential of an electron emitted very near the surface of the material, thus creating an image charge of itself. The work function then is the minimum energy for this electron to overcome the image potential of itself.

See, for example, Pg. 10 of this article, which is a common usage of work function in accelerator physics and photoinjectors:

https://indico.cern.ch/event/218284...ts/352241/490774/Part_1_-Electron_sources.pdf

It is why one can modify the work function via Schottky effect, resulting in a lower work function and thus, higher electron emission and higher QE.

Zz.
 
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Related to What were the real results of the photoelectric effect experiment?

1. What is the photoelectric effect experiment?

The photoelectric effect experiment is an experiment conducted by physicist Albert Einstein in 1905 to study the interaction between light and matter. It involves shining a beam of light on a metal surface and observing the emission of electrons from the surface.

2. What were the real results of the photoelectric effect experiment?

The real results of the photoelectric effect experiment showed that the energy of the emitted electrons was directly proportional to the frequency of the incident light, rather than its intensity. This relationship is known as the Einstein's photoelectric equation: E = hf, where E is the energy of the emitted electron, h is Planck's constant, and f is the frequency of the incident light.

3. How did the results of the photoelectric effect experiment contribute to the development of quantum mechanics?

The results of the photoelectric effect experiment provided evidence for the particle nature of light and the concept of quantization of energy. This led to the development of quantum mechanics, which revolutionized our understanding of the behavior of particles at the atomic and subatomic level.

4. Were there any limitations to the photoelectric effect experiment?

Yes, there were limitations to the photoelectric effect experiment. One limitation was that it only worked with certain types of metals and not all materials. Another limitation was that it could not explain the phenomenon of wave-particle duality, which was later addressed by the development of the wave mechanics theory.

5. How is the photoelectric effect experiment used in modern technology?

The photoelectric effect experiment has many practical applications in modern technology. It is the basis for the operation of devices such as solar panels, photodiodes, and photomultiplier tubes. It is also used in various types of sensors, such as light sensors and motion detectors, and in the development of advanced imaging techniques like electron microscopy.

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