# Confused about the Photoelectric Effect?

If an incident photon with frequency f hits a metal with a work force of w: How do I find the color of the incident photon and the threshold frequency of the metal?

I missed out on the days in my physics class where they covered work force and stopping voltage, so what equations are necessary to find the color and threshold frequency?

I know this is probably an easy question, but if you could please show me the steps with an explanation, that would really help me prepare for my test on Monday.

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A quick google search, and wikipedia read would probably be quite fruitful. –  zhermes Apr 28 '13 at 0:57
@zhermes - I've been searching for an hour and I have no idea how to find the frequency of metal, only the frequency of a photon. –  Genevieve Ccio Apr 28 '13 at 1:05
The very first article in a google search is wikipedia's photoelectric effect. The article defines a metal's threshold frequency within roughly the first page. –  zhermes Apr 28 '13 at 1:16

Photoeffect's main equation is one of energy balance. The only energy source in this event is the photon whose energy is $hf$. If that is enough to eject an electron ($\ge w$), the emission occurs. The leftover energy becomes kinetic energy of the electron. $$hf=w+K$$
The threshold is the case where you get just enough energy to emit the electron but no leftover. The needed equation is $$hf=w$$