PDA

View Full Version : PhotoElectric Effect Question

Panic Attack
Nov2-09, 08:32 PM
1. The problem statement, all variables and given/known data
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.


2. Relevant equations
KE = hc/wavelenght - Wo


3. 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)
Panic Attack
Nov2-09, 10:40 PM
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?
john54
Nov26-09, 09:22 AM
If it is not too late...

The max k.e. should be 8 eV
Panic Attack
Dec3-09, 07:13 PM
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?
Redbelly98
Dec5-09, 07:43 PM
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.)
Panic Attack
Dec6-09, 03:09 PM
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... :)