Electrical Technology

Study Preview Electricity transformed people’s lives beginning in the late 1800s with its application to all kinds of activities. The modern music industry sprang up around these new systems for recording and playing back sound. Radio and television, both rooted in electricity, were among the technologies around which entire new industries were created.

Learning Objectives By the end of this module you will be able to:

  1. 2.4.1 Evaluate the results of the U.S. prioritizing electricity access for citizens
  2. 2.4.2 Describe early developments in sound recording
  3. 2.4.3 Outline the evolution of electrical communication

2.4.1 Electricity as Transformational 1. Objective: Evaluate the results of the U.S. prioritizing electricity access for

citizens

The harnessing of electricity had a profound impact on American life beginning in the late 1800s. The infrastructure for an electricity-based lifestyle was wholly in place half a century later when, in the 1930s, the government launched a massive project to extend electricity-distribution networks to every end-of-the-road farmhouse. During this period, inventors and tinkerers came up with entirely new media of mass communication that went beyond books, newspapers, and magazines. In the span of a generation, people found themselves marveling at an impressive array of inventions ranging from the light bulb to streetcars. Among the new delights were phonographs,

radio, and then television.

Consider how much these new media transformed lifestyles. A person who as a child read at night by kerosene lantern could in adulthood be watching television.

Electricity can be generated through electric grids, nuclear reactors, solar cells, by water through hydropower—referred to as hydroelectric dams—and most recently, through wind-electric turbines. A small wind-electric turbine can generate enough electricity for one home, and a wind farm, depending on the size, can generate enough electricity for a community, often by contributing to the municipal electricity grid.

Granville Woods. New possibilities for communication were suggested in his invention of railway telegraphy in 1887. The invention allowed train conductors to communicate with each other in transit and with dispatchers.

2.4.2 Recording 1. Objective: Describe early developments in sound recording

Sound recording did not begin as an electronic medium. The first recording machine, the phonograph invented by Thomas Edison in 1877, was a cylinder wrapped in tinfoil that was rotated by hand as a singer shouted into a large metal funnel. The

funnel channeled the vibrations against a diaphragm, which fluttered and thus cut grooves into the rotating tin. When the cylinder was rotated in a playback machine, a stylus picked up sound from the varying depths of the groove. To hear the sound, a person placed his or her ear next to a megaphone-like horn and then rotated the cylinder.

Inherent in Edison’s system, however, was a major impediment for commercial success. A recording could not be duplicated, let alone mass-produced. In 1887, Emile Berliner introduced a sturdy metal disk to replace Edison’s foil-wrapped cylinder. From the metal disk, Berliner made a model and then poured thermoplastic material into the mold. When the material hardened, Berliner had a near-perfect copy of the original disk, and he could make hundreds of them. The process was primitive by today’s standards—entirely mechanical, nothing electronic about it. But it was a marvel at the time.

Watch Edison and the Phonograph View this video at: https://www.youtube.com/watch?v=1QwDEhR9JJg

2.4.3 Electromagnetic Spectrum 1. Objective: Outline the evolution of electrical communication

The introduction of electricity into mass communication occurred with the telegraph. After experimenting with sending electrical impulses by wire for more than a decade, Samuel Morse talked Congress into spending $30,000 to string electricity-conducting wires 41 miles from Washington to Baltimore. In 1844, using his code of dots and dashes, Morse sent the famous message “What hath God wrought.” The demonstration’s high visibility showed that real-time communication was possible over great distances. Morse’s instantaneous-communication gizmo overcame an

00:00 / 00:00

impediment of the printed word—the inherent delay of producing and delivering a physical product.

The possibilities of the Morse invention electrified people—and investors. By 1848, only four years later, promoters had rounded up the money to construct a system that linked the most populous parts of the United States—up and down the eastern seaboard and inland as far as Chicago and Milwaukee. By 1866, a cable had been laid on the floor of the Atlantic Ocean to connect North America with Europe for telegraphic communication.

Although telegraph messages basically were Point A to Point B communication, not mass communication, the path was opened for using electricity for communication to broad audiences—perhaps even without wires.

Wireless The suggestion of wireless communication was inherent in a discovery by Granville Woods in 1887. Woods devised a way to send messages to and from moving trains. Railway telegraphy, as it was called, allowed dispatchers to communicate in real-time with trains and prevent collisions. Although the invention was intended for electric trains, which drew their power from overhead lines and on-ground rails, Woods’ work also posed the question: Could communication be untethered?

For hundreds of years, scientists had had a sense that lightning emitted invisible but powerful electrical waves. The word radi, from the Latin radius, was used because these waves rippled out from the lightning. A German scientist, Heinrich Hertz, confirmed the existence of these waves in 1887 by constructing two separate coils of wire several feet apart. When electricity was applied to one coil, it electrified the other. Thus, electricity indeed could be sent through the air on what soon were called Hertzian waves.

The scientific journals, full of theories about Hertzian waves, intrigued a young nobleman in Italy, Guglielmo Marconi. Whether he realized it or not, Marconi’s reading was educating him as an engineer. Obsessed, refusing to take time even for food, he locked himself in an upstairs room at his father’s estate near Bologna and contemplated and fiddled. By grounding Hertz’s coils to the earth, Marconi discovered in 1895 that he could send messages farther and farther. Soon he was ringing a bell across the room by remote control, then downstairs, then 300 feet away —the first wireless messages.

Marconi became hopeful that he could disprove the contention among scientists that Hertzian waves could not penetrate solid objects let alone earth. He devised an antenna, which further extended transmission range. He also hooked up a Morse telegraph key, which was already being widely used to tap out dots and dashes for transmission on telegraph lines. Marconi had his brother travel 3 miles away over a hill with instructions to fire a rifle if the Morse letters, dot-dot-dot, came through a receiver. Metaphorically, it was a shot heard around the world.

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