Concept question photoelectric effect

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Kayko Lee 1C
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Joined: Wed Sep 30, 2020 9:39 pm

Concept question photoelectric effect

Postby Kayko Lee 1C » Mon Oct 19, 2020 8:50 pm

Describe the photoelectric effect qualitatively (in words) and quantitatively (using an equation). How did the findings of the photoelectric experiment contradict the wave model of light?
This was taken from one of the Week 2 workshops and I just wanted to double check what I had with anyone else to make sure that I have a clear understanding of the topic as I had to think a bit.

Isabella Chou 1A
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Re: Concept question photoelectric effect

Postby Isabella Chou 1A » Mon Oct 19, 2020 9:15 pm

The photoelectric effect tells us that light is made up of photons, and when trying to eject electrons from a metal surface, the energy of each photon must be sufficient to overcome the binding energy between the atom and the electron (or the threshold energy). Each photon interacts with one electron.
The equation for the photoelectric effect: E(photon) - Φ (work function) = Ek
According to the wave model of light, increasing the intensity of light shone on a metal surface should eject electrons because a wave with higher intensity should have more energy. However, the photoelectric experiment revealed that increasing intensity does not eject the electron if the light source does not have a high enough frequency. In this case, increasing intensity with a low frequency light source only increases the number of photons, not the individual energy of each photon. Thus, each individual photon must have sufficient energy to remove each electron, which explains the photon model of light.


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