- #1
Supitha
- 4
- 2
- 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
- Start date
Click For Summary
Discussion Overview
The discussion revolves around the photoelectric effect, specifically addressing differences in observed phenomena represented by figures, the role of photon energy and intensity, and the concept of the work function. Participants explore theoretical aspects and implications of experimental observations.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant questions the difference between two figures related to the photoelectric effect, seeking clarification on the red and green lines.
- Another participant introduces the concept of the work function, suggesting that even at zero applied voltage, there exists a "virtual" voltage that affects electron emission, particularly at different photon frequencies.
- There is a suggestion that at low photon frequencies, the likelihood of electrons escaping the metal is reduced due to insufficient energy, while higher photon energies increase the chances of overcoming the work function threshold.
- A participant speculates that the second figure likely illustrates two different light intensities at the same wavelength, explaining that higher intensity results in more photons and consequently more electrons being emitted.
- Discussion includes the idea that all curves in the first figure represent the same intensity, leading to saturation at a consistent number of emitted electrons per second regardless of increased applied voltage.
Areas of Agreement / Disagreement
Participants express differing views on the interpretation of the figures and the implications of photon energy and intensity on electron emission. No consensus is reached regarding the specific explanations for the observed phenomena.
Contextual Notes
Some assumptions about the definitions of terms like "work function" and "stopping potential" remain unclarified, and the discussion does not resolve the underlying mathematical relationships or experimental conditions that may affect the observations.
- #2
Swamp Thing
- 1,047
- 793
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
- 2
What's happenning in second one?
- #5
Supitha
- 4
- 2
No. The second picKizer said:
- #6
Swamp Thing
- 1,047
- 793
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.
Similar threads
- · Replies 11 ·
- · Replies 10 ·
- · Replies 5 ·
- · Replies 5 ·
- · Replies 12 ·
- · Replies 0 ·
- · Replies 13 ·
- · Replies 30 ·
- · Replies 3 ·
High School
Photoelectric effect and atomic excitation
- · Replies 3 ·