电视、电话、收音机、电脑的发展及影响.pptVIP

By 15 An American physicist Reginald Fessenden in 1901,developed a device which could carry a signal in the audio frequency range. This enabled voice and music to be transmitted directly. Then, an American physicist Lee De Forest improved the whole detection system. But at that time, radio was used for transmission from one point to another. In 1916, David Sarnoff, an emigrant employee of Marconi’s company, had plans for profitable radio broadcasting. The growing broadcasting radio business served many functions. For the isolated farmers, radio provided entertainment and information, and served to unify these separated families into one country. For the urban newcomers, the radio also served to connect them with “neighbors”. And radio was an important locus of advertisements for the products to feed a growing consumerism in America. The development of TV In 1926, Baird, a British man, invented TV In 1930, sounds paced up with images. In 1972, color TV was invented in Japan. Now, we have liquid crystal TV set. The pioneers of TV believed that the primary use of this new device could be educational. But experience showed that the average person was bored with educational programs, and that sports activities, quiz shows were more to his liking. Furthermore, already busy Americans seemed to be able to find time to watch televisions. At the end of the century, it was apparent that American schoolchildren were spending less time studying, and less time playing sports and more time sitting passively in front of a TV set. Adults too were turning into “couch potatoes” much to the alarm of health officials The development of telephone The effect of telephone It is convenient for people to talk with others. A wire can lead him/her to others. Now, people can use it to surf the Internet, play games. Electronic computers were developed to be use in US military. These machines were enormous in size, using miles of wires and thousands of vacuum tubes. In 1947,the tr