The Photoelectric Effect

Abstract

We are aware of light (the term “light” is used here to include a wide range of electromagnetic radiations)—or perhaps we postulate with conviction the existence of a physical entity that we chose to call light—because we observe the effects when it interacts with, or is absorbed by, electrons, atoms, and matter. The sun radiates light; we feel its warmth on our skin, which we attribute to its infrared content; we suffer the effect of its destructive influence when we get sunburnt, and we attribute this to its ultraviolet content; but most obviously, we detect the radiations within a certain frequency window by the receptors in our eyes, which are tuned to recognize a certain spectrum of frequencies in the light. And, apart from our own personal experiences through our senses, we can build detectors that can provide information on the spectral distribution of intensity and frequency of radiation.