How to Calculate the Maximum Energy of Ejected Electrons?

Panic Attack
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Homework Statement


What is the maximum energy of the ejected electrons? When the radiation wavelength is 100 nm, and the stopping potential of the metal is 8.


Homework Equations


KE = hc/wavelenght - Wo


The Attempt at a Solution


I found the work function and the cut off wavelength to be the following but I can't figure out the max energy...

KE = hc/wavelenght - Wo

Wo = work function = { (6.63 *10^-34)(3*10^8) / (100 *10^9) } - (1.6*10^-19)(8)
Fo = cut off frequency = Wo / (6.63 *10^-34)
 
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I think I have an answer, but I don't know if it is right...

E = Wo + KE, where Wo = 1.225*10^-19, in which I solved for
E = hc/lambda = 6.62*10^-34 * 3*10^8 / 150*10^-19 = 1.324*10^-18

E = Wo + KE
1.324*10^-18 = 1.225*10^-19 + KE

KE = 1.2015*10^-19?

Can someone tell me if this is right?
 
If it is not too late...

The max k.e. should be 8 eV
 
john54 said:
If it is not too late...

The max k.e. should be 8 eV

It's never too late. I think I got this problem wrong then. Can you explain how you got 8?
 
Panic Attack said:
KE = hc/wavelenght - Wo
You are given wavelength and Wo in the problem statement, and are asked to calculate KE. You seem to be over-complicating things. (The answer is not 8 eV, by the way.)
 
Redbelly98 said:
You are given wavelength and Wo in the problem statement, and are asked to calculate KE. You seem to be over-complicating things. (The answer is not 8 eV, by the way.)

teheheh... I got it right den... :)
 
To solve this, I first used the units to work out that a= m* a/m, i.e. t=z/λ. This would allow you to determine the time duration within an interval section by section and then add this to the previous ones to obtain the age of the respective layer. However, this would require a constant thickness per year for each interval. However, since this is most likely not the case, my next consideration was that the age must be the integral of a 1/λ(z) function, which I cannot model.
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