Calculating Maximum Kinetic Energy of Ejected Electrons After Wavelength Doubles

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SUMMARY

The maximum kinetic energy of ejected electrons when the wavelength of incident photons doubles can be calculated using the equation Ekmax = (h×c/λ) - (e×Vs - E). Given that the energy of the photons is 12 eV and the stopping potential is 8.0 V, the relationship between energy, wavelength, and stopping potential is crucial. Doubling the wavelength effectively reduces the energy of the photons, which directly impacts the kinetic energy of the ejected electrons.

PREREQUISITES
  • Understanding of the photoelectric effect and its equations
  • Familiarity with Planck's constant (h) and the speed of light (c)
  • Knowledge of electron volt (eV) as a unit of energy
  • Ability to manipulate algebraic equations to solve for variables
NEXT STEPS
  • Study the photoelectric effect and its mathematical formulations
  • Learn how to derive relationships between energy, frequency, and wavelength
  • Explore the implications of stopping potential in photoelectric experiments
  • Practice problems involving kinetic energy calculations in the context of photon interactions
USEFUL FOR

Students in physics, particularly those studying quantum mechanics and the photoelectric effect, as well as educators looking for clear explanations of kinetic energy calculations in photon interactions.

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Homework Statement



Photons of energy 12 eV are incident on a metal. It is found that current flows from the metal until a stopping potential of 8.0 V is applied.
If the wavelength of the incident photons is doubled, what is the maximum kinetic energy of the ejected electrons?

Homework Equations



I am absolutely clueless. I feel like I'm supposed to use KE = hf - W but how am I supposed to know the frequency if it isn't given? So I don't think I'm supposed to use this one.
Please just lead me towards the right direction. I don't have a clue as to which equation to use.

The Attempt at a Solution



This question is gibberish to me and I don't know how to even approach it. Please help.
 
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Fair enough, did you look at the third link on Google? The Yahoo Answer one?
 


JameB said:
Fair enough, did you look at the third link on Google? The Yahoo Answer one?

Yes but it doesn't say how you get wavelength. Although E = hf and f = c/wavelength.
E = h(c/wavelength). In which case what is E?
 


It does. What that person did was used the relevant equations and formulated an equation that related the wavelength to the maximum energy.

Ekmax = (h×c/λ) - (e×Vs-E)

Now plug in the data you know, and use two variables for the wavelength and solve for the ratio.
 

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