Photo-electric Conduction in Selenium

Abstract

Variation with light intensity of the photo-current in selenium.—A selenium cell is described which gives a photo-current of 10 ma. for a difference of potential of 100 volts and an illumination of 100 foot-candles. The sensitiveness ratio between the currents under light and dark conditions is 100. The characteristics of the cell are very constant. The experimental results establish the existence of a linear relation between the square of the photo-current and the light intensity. It is pointed out that this result substantiates the conclusion that the photo-conduction in selenium is due to a photo-electric liberation of electrons rather than to an allotropic change from an insulating to a conducting form of selenium.