Photo electri question longest wave length

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Homework Help Overview

The problem involves a photoelectric experiment where electrons are emitted from a surface illuminated by light of a specific wavelength. The stopping potential for the emitted electrons is given, and the task is to determine the longest wavelength of light that can still produce a photoelectric current.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the energy of photons at the given wavelength and the energy associated with the stopping potential. There are inquiries about the relevant equations and how to relate frequency to wavelength.

Discussion Status

Some participants have provided hints regarding the relationship between photon energy and stopping potential, while others are exploring relevant equations and concepts from the photoelectric effect. There is an indication of progress as one participant expresses understanding after receiving guidance.

Contextual Notes

The original poster expresses uncertainty about how to begin the problem and seeks hints rather than direct answers. There is a mention of needing to convert frequency to wavelength and understanding the work function in relation to the stopping potential.

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Homework Statement


In a photoelectricc experiment,electrons are emitted from a surface illuminated by light of wavelength of 4000*(10^-10), and the stopping potential for these electron is found to be 0.5V. what is the longest wavelength of light that can illuminate this surface and still produce photoelectric current.


Homework Equations


not sure


The Attempt at a Solution


i need help to start the question because i have to clue how to start it... so could someine give me a hint on how to start it..NOT ASKING FOR ANSWER
 
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How much energy does a photon of that wavelength have.
How much energy does an electron lose going through 0.5V
= the energy the photon had left after being emitted

From this you can work out how much energy it took to emit it
 
http://en.wikipedia.org/wiki/Photoelectric_effect#Mathematical_description

Are you familiar with the equations written there?
If yes, simply convert frequency to wavelength (with constants multiplying it, of course) and realize that your stopping potential is their work function. If you do this properly, you will be able to 'see' how to find the longest wavelength.

If not, I'd recommend reading the article from start, or pick up any entry level book in Modern Physics (or maybe University Physics?).
 
i have seen some but not all... I am trying to work it out now
 
i see got it. thanks Sourabh N

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