# PhotoElectric Effect Question

## 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

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
Staff Emeritus