# Homework Help: Given energy, calculate electrons emitted

1. Oct 17, 2009

### ill

1. The problem statement, all variables and given/known data
What is the maximum number of electrons that can be freed by a burst of light whose total energy is 1.16 µJ?

2. Relevant equations
E=hv
v=c/$$\lambda$$

3. The attempt at a solution
I have no problem calculating frequencies and wavelengths, my issue is how can I use these numbers to relate to number of electrons emitted. Our book tells us that light with a frequency of 4.60X10^14 s^-1 or greater will cause cesium metal to emit electrons...the above frequency comes out to 1.75X10^27 meaning it will emit electrons....what I need is some equation that relates electron emission to any of the aforementioned quantities I can find.

2. Oct 17, 2009

### ideasrule

Undoubtedly, the 1.16 uJ is not concentrated in a single photon; it's spread out over many photons. What frequency should the photons be so that they can liberate the maximum number of electrons?