Photoelectric Effect: Wavelengths & Metals

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Discussion Overview

The discussion revolves around the photoelectric effect, specifically focusing on the wavelengths required to induce this effect in metals such as stainless steel and aluminum. Participants explore the energy levels associated with different wavelengths and the implications of applying external factors like voltage and temperature.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Participants inquire about the specific wavelengths that can induce the photoelectric effect in stainless steel and aluminum.
  • Some participants note that the photoelectric effect requires a minimum energy, which corresponds to specific wavelengths for different metals.
  • One participant suggests that aluminum, with a work function of 4.08 eV, would require a wavelength of around 304nm, indicating that 380nm is insufficient for the photoelectric effect in this metal.
  • Another participant questions whether applying a high voltage could extend the wavelength needed for the photoelectric effect.
  • There is mention of research indicating that the work function may be lower when metals are exposed to vacuum and an electric field.
  • One participant proposes that heating the material could facilitate thermionic emission, potentially requiring less energy from incident light to excite electrons.

Areas of Agreement / Disagreement

Participants generally agree that 380nm light is not sufficient for inducing the photoelectric effect in aluminum, but there is no consensus on the effects of high voltage or heating on the required wavelengths.

Contextual Notes

There are unresolved assumptions regarding the specific conditions under which the photoelectric effect can be observed, including the influence of external factors like vacuum and electric fields, as well as the implications of thermionic emission.

Who May Find This Useful

This discussion may be useful for individuals interested in experimental physics, particularly those exploring the photoelectric effect and its dependencies on material properties and external conditions.

HMS-776
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I have a few questions on the Photoelectric Effect.

First off, what wavelengths could be used to cause a photoelectric on Stainless Steel?

What widely available metals have the lowest eV for the photoelectric effect?

Could a UV light of 380nm work to cause a photoelectric effect on Stainless steel or aluminum? Or does it have to be the exact energy level?
 
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HMS-776 said:
Could a UV light of 380nm work to cause a photoelectric effect on Stainless steel or aluminum? Or does it have to be the exact energy level?

Aluminium would be your best bet (it is one of the most common metals and has a fairly low work function (4.08 eV). However, this corresponds to a wavelength of 304nm, so 380nm isn't short enough. The photons in the 380nm light will only have 3.3eV, enough to ionise sodium, potassium, cesium and any other metals with only 1 electron in the outer shell. These metals are pretty hard to get hold of though I would imagine, so I'm not sure you could do any experiments of this kind without a different UV source!

Source: http://hyperphysics.phy-astr.gsu.edu/HBASE/Tables/photoelec.html
 
I understand now that it wouldn't work with 380nm. Looks like I would need something around 300nm. Too expensive for now...


Thanks everyone for the help!
 
What if a high voltage is applied, will it have any effect on lengthening the wavelength needed?
 
Hi HMS I read many papers stating that the work function lower in the case it is exposed to vacuum and an electric field.
 
I would expect heating it would help out. Heating up the material can cause thermionic emission without the incident light. Basically, the electrons would be excited thermally to higher states requiring less photonic energy.
 

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