Willoughby Smith Discovers the Photoconductivity of Selenium

1873
Upper cover of the presentation copy from Smith in the Library of the Royal College of Surgeons of England. This was a paper read to the Society of Telegraph Engineers on November 28, 1877.
Image Source: archive.org
Upper cover of the presentation copy from Smith of his paper, Selenium: Its Electrical Qualities and the Effect of Light Thereon,  in the Library of the Royal College of Surgeons of England. This was a paper read to the Society of Telegraph Engineers on November 28, 1877.
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photo of Willoughby Smith
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Willoughby Smith

In 1873 English electrical engineer Willoughby Smith discovered that the electrical resistance of selenium varies dramatically with the amount of light falling on it. The photoconductivity of selenium eventually provided a method for converting images into electrical signals—the basis for photoelectric cells and a theoretical basis for television. 

Timeline Themes

Technology / Engineering
Television
Upper cover of the presentation copy from Smith in the Library of the Royal College of Surgeons of England. This was a paper read to the Society of Telegraph Engineers on November 28, 1877.
Image Source: archive.org
Upper cover of the presentation copy from Smith of his paper, Selenium: Its Electrical Qualities and the Effect of Light Thereon,  in the Library of the Royal College of Surgeons of England. This was a paper read to the Society of Telegraph Engineers on November 28, 1877.