Help on KE of photoelectron emmision

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Homework Help Overview

The discussion revolves around the photoelectric effect, specifically focusing on calculating the kinetic energy of emitted photoelectrons when light of a certain wavelength strikes an aluminium surface. The work function of aluminium is also a key factor in the problem.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • The original poster attempts to calculate the maximum kinetic energy of photoelectrons using the equation KE max = hf - W, where W is the work function. They express uncertainty about the correct equations and seek guidance. Other participants question the method for determining the slowest emitted electrons and the cutoff wavelength, suggesting a need to understand the relationship between energy, frequency, and wavelength.

Discussion Status

Participants are actively engaging with the problem, exploring different aspects of the photoelectric effect. Some guidance has been provided regarding the threshold frequency and the relationship to the cutoff wavelength. There is a collaborative atmosphere, with participants confirming each other's thoughts and clarifying concepts.

Contextual Notes

The original poster indicates a novice level of understanding and seeks foundational guidance on the relevant equations and concepts. There is an emphasis on understanding the relationship between kinetic energy, work function, and emitted electron characteristics.

carus88
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'light of wavelength 180nm falls on an aluminium surface. the work funct is 4.2eV.
what is the KE of the fastest and slowest emmited photoelectrons?
Also the cutoff wavelength for the Aluminium?
i only need the right equations an a little guidance as i myt as well be a complete novice.

i have worked out what i think is the max KE as 2.69eV

using KE max = hf - W (w as the work funct)
 
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The second part asks for kinetic energy of the slowest emitted electrons. What do you imagine is the slowest speed an electron can be emitted? The cutoff wavelength is just that wavelength that provides the same energy of the work function.
 
so i use the work funct equation an work backwards to get the threshold freq an then the cut off wavelength?

and for the min KE use the threshold freq?
 
exactly! :smile:
 
thank you so much!
 

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