What is working principal of xerox machine?
The Xerox photocopier was a machine designed by an engineer working as a patent attorney. The principle is to spray electric charge upon the smooth surface of a semiconductor, and then flash an image of the material to be copied onto this plate. The light causes the plate to discharge in that local area, and when pigment powder is sprinkled over the plate, it sticks to the charged spots and falls off the discharged spots. The plate is then placed in contact with a blank sheet of paper to which the powder is transferred, then the paper is heated to stick the pigment to the paper.