AST 101 Lecture Notes - Lecture 7: Chromatic Aberration, Curved Mirror, Primary Mirror
Document Summary
Light is transmitted by photons -- discrete units of light that each carry a specific amount of energy. The key to understanding this was the study of the photoelectric effect. When one shines light on a metallic surface, that can result in electrons being ejected from the surface. The brighter the light, the more ejected electrons. But for any given material, there is a maximum wavelength of light that will result in the photoelectric effect. This last bit only makes sense if the energy of light is contained in discrete bundles or photons, in which the energy of the photon corresponds to the wavelength of the light. This was pointed out in 1905 by albert einstein, and is the work for which einstein was awarded the nobel prize. Red light photons have less energy than do blue light photons. This is expressed in what is known as planck"s law (named for max planck):
