science · 21 October 1925 · 100 years ago
In 1925, the photocell device was given its first U.S. public demonstration. It was shown by the Westinghouse Electric and Mfg Co at the Electrical Show at Grand Central Palace in New York. The photocell was used to count objects by acting as a sensor as each object passed through and interrupted a beam of light. The device was also utilized as a sensor to detect when a person approached a door, which opened as a circuit was activated.
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