In the early 1900's, the world was developing at a very rapid pace, and with the growth of industrialization, cities became more crowded. Furthermore, with the invention automobiles, the traffic on the roads increased significantly, so there was a need for a better traffic system. In 1912, an American policeman, Lester Wire, who was concerned with the increasing traffic, came up with the idea of the first electric traffic light. Based on Wire's design, the lights were first installed in Cleveland, Ohio, on August 5, 1914, at the corner of 105th and Euclid Avenue The first electric traffic light had only red and green lights; it did not have a yellow light like modern- day traffic signals. Instead of a yellow light, it had a buzzer sound that was used to indicate that the signal would be changing soon. In the year 1920, a policeman named William Potts in Detroit, Michigan invented the first four-way and three-coloured traffic lights. Apart from red and green, a third colour - amber (or yellow) - was introduced. Detroit became the first city to implement the four-way and three-colored traffic lights. In the 1920's, several automated traffic signals were installed in major cities around the world. The modern traffic light still uses this famous T-shaped model with three different colors. . Answer the questions 1.When was the first electric traffic light invented? _______________________________________________ 2Who invented the first electric traffic light? _______________________________________________ 3.How many colours did the first electric traffic light have? _______________________________________________ 4.Where were the lights first installed? _______________________________________________ 5.What was used instead of yellow light to warn everyone of a signal change? ______________________________________6.When was the yellow light added? ________________________________________________
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Sinh Học lớp 12
