Photoelectric effect  [ENDORSED]

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Husnia Safi - 1K
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Joined: Fri Sep 29, 2017 7:04 am

Photoelectric effect

Postby Husnia Safi - 1K » Sun Oct 15, 2017 8:47 pm

Hi can someone please give me a simple summary on the significance of the photoelectric effect?

Andrea Grigsby 1I
Posts: 60
Joined: Fri Sep 29, 2017 7:03 am

Re: Photoelectric effect

Postby Andrea Grigsby 1I » Sun Oct 15, 2017 9:11 pm

An experiment showed that if a light beam had high enough frequency it could make a surface eject an electron. The emphasis is on frequency here as the intensity of the light had no effect on the electron, which showed that the light was not acting like a classic wave.
--> this boils down to the idea of photons and how each photon of light must have enough energy to eject an electron

Harrison Wang 1H
Posts: 50
Joined: Fri Sep 29, 2017 7:07 am

Re: Photoelectric effect

Postby Harrison Wang 1H » Sun Oct 15, 2017 9:30 pm

To build on what Andrea said, raising the intensity of light just increased the number of photons, and without sufficient frequency these photons were still unable to eject electrons.

Posts: 18
Joined: Sat Jul 22, 2017 3:01 am

Re: Photoelectric effect

Postby Christietan3F » Sun Oct 15, 2017 10:49 pm

Photons at an individual level must have enough energy to displace electrons. Increasing the intensity of the light just increases the amount of photons that are unable to displace an electron.

Diane Bui 2J
Posts: 61
Joined: Sat Jul 22, 2017 3:00 am

Re: Photoelectric effect  [ENDORSED]

Postby Diane Bui 2J » Sun Oct 15, 2017 11:44 pm

Based off of what I remembered from lecture and my notes, the photoelectric effect was an experiment that was testing the threshold energy of a metal. Light was shone on a metal surface to measure the energy needed to remove electrons from the metal. What was unexpected was that electrons were not emitted even under high intensity light. Based on the wave model of light, higher intensity means greater wavelength and greater wave amplitude. Because electrons were still not emitted, the experiment gave rise to the particle model of light, in which light is considered as photons (packets) of energy where one photon interacts with one electron at the surface of a metal. Based on the particle model of light, increasing intensity means increasing number of photons, but if each photon does not have enough energy, the electron is not removed. Based off of E=hv, increasing frequency (which accordingly means lowering wavelength) will increase the energy of the photon and the electron will be removed.

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