- #1
Supitha
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- How can explain the difference of these red dots?
- Red line = Green line ?. How to explain it?
2 questions about the photo electric effect
- Context: High School
- Thread starter Supitha
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SUMMARY
The discussion focuses on the photoelectric effect, specifically the relationship between photon frequency, work function, and electron emission. It is established that at low photon frequencies, the likelihood of electrons escaping the metal is reduced due to insufficient energy, while higher photon energies increase the probability of overcoming the work function threshold. Additionally, the conversation highlights that increasing light intensity at the same wavelength results in more electrons being emitted, as more photons per second lead to a higher current flow, despite the stopping potential remaining constant.
PREREQUISITES- Understanding of the photoelectric effect
- Familiarity with concepts of work function and stopping potential
- Knowledge of photon energy and its relation to electron emission
- Basic principles of light intensity and its impact on electron flow
- Research the mathematical formulation of the photoelectric effect using Einstein's equation
- Explore the concept of work function in different materials and its implications
- Investigate the role of intensity in the photoelectric effect and its practical applications
- Learn about experimental setups to measure stopping potential and electron emission rates
Students of physics, educators teaching the photoelectric effect, and researchers exploring quantum mechanics and electron behavior in materials.
- #2
Swamp Thing
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Even when the applied voltage is zero, there is a kind of "virtual" voltage that pulls the electrons back into the metal. This is called the "work function", I believe.
So at low photon frequencies, there is a smaller chance that an electron will end up with enough energy to leave the metal (because total energy = photon energy + random thermal energy). For high photon energies, there is more chance of escaping i.e. more chance that electron's original thermal energy plus photon energy will carry it over the work function threshold.
So at low photon frequencies, there is a smaller chance that an electron will end up with enough energy to leave the metal (because total energy = photon energy + random thermal energy). For high photon energies, there is more chance of escaping i.e. more chance that electron's original thermal energy plus photon energy will carry it over the work function threshold.
- #3
Supitha
- 4
- 2
Thank you so much.Swamp Thing said:
- #4
Supitha
- 4
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What's happenning in second one?
- #5
Supitha
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No. The second picKizer said:
- #6
Swamp Thing
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I'm guessing here, but the second figure probably shows two different intensities at the same wavelength. The "stopping potential" is the same for both curves because the photon energy is the same, but once you allow some current to flow then the more intense light means more photons per second which means more electrons per second.
Going back to fig. 1, all curves involve the same intensity (same rate of photons per second) so they all saturate at the same number of electrons per second. If you increase the applied voltage to a huge value, you can still pull only those electrons that are liberated by photons, so "pulling harder" won't make much difference -- so the curves saturate at some point.
Going back to fig. 1, all curves involve the same intensity (same rate of photons per second) so they all saturate at the same number of electrons per second. If you increase the applied voltage to a huge value, you can still pull only those electrons that are liberated by photons, so "pulling harder" won't make much difference -- so the curves saturate at some point.
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