Wife texts husband on a cold winter morning: "Windows frozen, won't open."
Husband texts back: "Gently pour some lukewarm water over it and then gently tap edges with hammer."
Wife texts back 10 minutes later: "Computer really messed up now."
Photoelectric cellIn 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.« |
