Selenium is a light-sensitive material that generates an electrical current when exposed to light, particularly when used in a barrier layer construction. This property makes it useful in photographic exposure meters, where it helps measure the intensity of light to determine correct exposure settings.
Historically, selenium cells were widely used in analog light meters and some early cameras, providing accurate, reliable exposure readings without the need for batteries. Understanding selenium’s role in photography highlights the evolution of light metering technology and its impact on achieving properly exposed images.