# Why doesn't intensity of light affect the emission of electrons?

So electrons of specific atoms have a minimum amount of energy needed to escape the atom, called the work function, W. Now let's say that you emit a certain frequency of light, and $hf<W$. However, from my understanding, this work function is just a form of kinetic energy, and if an electron has enough kinetic energy, its inertia will be greater than the centripetal force and the electron will escape. So even though $hf<W$, the object being illuminated will still heat up from the light. This heating up means that the material is gaining internal energy, which means that the electrons are gaining kinetic energy. If the material gets hot enough and the electrons keep gaining speed, couldn't the they escape anyway even though $hf<W$? Thanks!

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– Brandon Enright May 9 '13 at 23:08
At sufficiently high intensities there are exceptions to this rule. You should not however take this as a refutation of the quantum hypothesis, because it strengthens it. The dependence of multi-photon processes on intensity can only be explained by quantum mechanics. Learn and understand the basic quantum explanation of the photo-electric effect and keep this exception in mind for the future. – dmckee May 9 '13 at 23:56