Electricity and Electronics
Electricity and Electronics
ELECTRICITY AND ELECTRONICS
ELECTRICITY AND ELECTRONICS. In December 1879 Thomas Alva Edison and his associates invited the public to their work site in Menlo Park, New Jersey. People from New York and elsewhere gathered to see what they had never seen before—buildings and grounds illuminated with about 100 electric incandescent lamps.
By the time of Edison's Menlo Park demonstration, much had already been discovered about electricity. The Italian scientist Alessandro Volta had invented the electric battery, and the English scientist Michael Faraday had created a generator using magnetism to produce electricity. Even the idea of electric lighting was not new.
Various scientists and inventors in different parts of the world were working to develop forms of electric lighting, but until that time nothing had been developed that was practical for home use. Commercial and street lighting were powered by gas and carbon-arc systems. The latter produced an extremely bright light by sending electricity across a gap between two carbon terminals.
By contrast, an incandescent lamp produced a much less intense light by passing electricity through a filament, or wire, which would then glow. But what was the best filament to use? Edison and his associates spent months searching. They first experimented with a platinum filament, but this metal was quick to overheat and burn out. Success finally came when they tested a carbon filament made from burned sewing thread and improved the vacuum inside the bulb. The carbonized sewing thread burned for thirteen and a half hours and was used in their public demonstration. Later, they made bulbs with bamboo filaments, which extended the life of the bulbs even further.
At first, Edison's electric light was a mere novelty because few homes and businesses had electricity. To make his invention practical for everyday use, electricity had to be readily available to customers. Edison spent the next several years creating the electric industry, a system of producing electricity in central power plants and distributing it over wires to homes and businesses. Before long, electrical power would spread around the world.
What Is Electricity?
Electricity, a form of energy, occurs from the flow of electrons, or negatively charged particles. The number of electrons in an atom usually equals the number of protons, or positively charged particles. When this balance is upset, such as when two distinct surfaces are rubbed together, an atom may gain or lose an electron. The resulting free movement of a "lost" electron is what creates an electric current.
The phenomenon of electricity had been observed, though not understood, by ancient Greeks around 600 b.c. They found that by rubbing amber, a fossilized resin, against a fur cloth, they could create a tiny spark. In 1752 Benjamin Franklin proved that electricity is a basic part of nature and that lightning and the spark from amber were one and the same. He did this, in his now famous experiment, by fastening a wire to a silk kite and flying it during a thunderstorm. Franklin held the end of the kite string by an iron key. When a bolt of lightning struck the wire, it traveled down the kite string to the key and caused a spark.
Not only did Franklin prove that lightning was electricity, he theorized that electricity was a type of fluid that attracted or repulsed materials—an idea that continues to help scientists describe and understand the basics of electricity.
While electricity is a form of energy, it is not an energy source. It is not harvested or mined; it must be manufactured. Electricity comes from the conversion of other sources of energy, such as coal, natural gas, oil, nuclear power, solar power, and others. And because it is not easily stored in quantity, electricity must be manufactured at or near the time of demand.
In 1881 Edison and his associates moved to New York City to promote the construction of electric power plants in cities. They invested in companies that manufactured products—generators, power cables, electric lamps, and lighting fixtures—that were needed for a commercially
successful electric lighting system. They also built the Pearl Street Station, a steam electric power plant near Wall Street. On 4 September 1882, this power plant began providing light and power to customers in a one-square-mile area.
A model of efficiency for its time, Pearl Street used one-third the fuel of its predecessors, burning about ten pounds of coal per kilowatt-hour, a unit of electric power equal to the work done by one kilowatt acting for one hour. Initially the Pearl Street utility served fifty-nine customers for about twenty-four cents per kilowatt-hour.
In the late 1880s power demand for electric motors brought the industry from mainly nighttime lighting to twenty-four-hour service. Soon, small central stations dotted many U.S. cities. However, each was limited to an area of only a few blocks because of transmission inefficiencies of direct current (DC).
A breakthrough came in 1888 when the Serbian-born American Nikola Tesla discovered the principles of alternating current (AC), a type of electric current that reverses direction at regular intervals and uses transformers to transmit large blocks of electrical power at high voltages. (Voltage refers to the pressure or force that causes electrons to move.) Tesla went on to patent a motor that generated AC. Around the turn of the twentieth century, it was clear that the future of electricity in this country and elsewhere lay with AC rather than DC.
The first commercial electric power plant to use AC began operating in the United States in 1893. Built by the Redlands Electric Light and Power Company, the Mill Creek plant in California transmitted power 7.5 miles away to the city of Redlands. The electricity was used for lighting and for running a local ice house.
Two years later, on 26 August 1895, water flowing over Niagara Falls was diverted through two high-speed turbines connected to two 5,000-horsepower AC generators. Initially, local manufacturing plants used most of the electricity. But before long, electricity was being transmitted twenty miles to Buffalo, where it was used for lighting and for streetcars.
This new source of energy had so many practical applications that it greatly changed the way people lived. Inventors and scientists developed electric devices that enabled people to communicate across great distances and to process information quickly. The demand for electric energy grew steadily during the 1900s.
The technical aspects of the generation and transmission of electricity continued to evolve, as did the electric utility industry. Clearly, large-scale power plants and the electricity they produced were major forces that shaped life in twentieth-century America.
The world's reliance on electronics is so great that commentators claim people live in an "electronic age." People are surrounded by electronics—televisions, radios, computers, and DVD players, along with products with major electric components, such as microwave ovens, refrigerators, and other kitchen appliances, as well as hearing aids and medical instruments.
A branch of physics, electronics deals with how electrons move to create electricity and how that electric signal is carried in electric products. An electric signal is simply an electric current or voltage modified in some way to represent information, such as sound, pictures, numbers, letters, or computer instructions. Signals can also be used to count objects, to measure time or temperature, or to detect chemicals or radioactive materials.
Electronics depend on certain highly specialized components, such as transistors and integrated circuits, which are part of almost every electronic product. These devices can manipulate signals extremely quickly; some can respond to signals billions of times per second. They are also extremely tiny. Manufacturers create millions of these microscopic electronic components on a piece of material—called a chip or a microchip—that is no larger than a fingernail. Designing and producing microscopic electronic components is often referred to as microelectronics or nanotechnology.
The development, manufacture, and sales of electronic products make up one of the largest and most important industries in the world. The electronics industry is also one of the fastest growing of all industries. The United States and Japan are the world's largest producers of electronic components and products. In the mid-1990s, electronics companies in the United States had sales that totaled more than $250 billion. During the same period, Japanese firms had sales that totaled more than $200 billion in U.S. dollars.
Areas of Impact
Communication. Electronic communication systems connect people around the world. Using telephones and computers, people in different countries communicate almost instantly. Radios transmit sounds and televisions transmit sounds and pictures great distances. Cellular telephones enable a person to call another person while riding in a car, walking down the street, or hiking in the woods. Within seconds, fax machines send and receive copies of documents over telephone lines.
Information processing. Scientists, artists, students, government and business workers, and hobbyists at home all rely on computers to handle huge amounts of information quickly and accurately. Computers solve difficult mathematical problems, maintain vast amounts of data, create complex simulations, and perform a multitude of other tasks that help people in their everyday lives. Many computer users also have instant access to the Internet, which offers a wide variety of information and other features.
Medicine and research. Physicians use a variety of electronic instruments and machines to diagnose and treat disorders. For example, X-ray machines use radiation to take images of bones and internal organs. The radiation is produced in a type of electronic vacuum tube. Radiation therapy, or radiotherapy, uses X-rays and other forms of radiation to fight cancer. Many hearing-impaired people depend on hearing aids to electrically amplify sound waves.
Computers and other electronic instruments provide scientists and other researchers with powerful tools to better understand their area of study. Computers, for example, help scientists design new drug molecules, track weather systems, and test theories about how galaxies and stars develop. Electron microscopes use electrons rather than visible light to magnify specimens 1 million times or more.
Automation. Electronic components enable many common home appliances, such as refrigerators, washing machines, and toasters, to function smoothly and efficiently. People can electronically program coffeemakers, lawn sprinklers, and many other products to turn on and off automatically. Microwave ovens heat food quickly by penetrating it with short radio waves produced by a vacuum tube.
Many automobiles have electronic controls in their engines and fuel systems. Electronic devices also control air bags, which inflate to protect a driver and passengers in a collision.
Edison's carbonized sewing thread and bamboo filaments were not used in incandescent bulbs for long. Around 1910, chemists at the General Electric Company developed a much improved filament material—tungsten. This metal offered many advantages over its predecessors—a higher melting point, a tensile strength greater than steel, a much brighter light, and it could easily be shaped into coils. So good was tungsten that it is still used in incandescent lightbulbs. But today, incandescent lightbulbs are not the only option for consumers. Other lighting choices include fluorescent and halogen lamps. Fluorescent lamps produce light by passing electricity through mercury vapor, causing the fluorescent coating to glow. This type of light is common outdoors and in industrial and commercial uses. Another type of incandescent lamp, called halogen, produces light using a halogen gas, such as iodine or bromine, that causes the evaporating tungsten to be returned to the filament. Halogen bulbs are often used in desk and reading lamps. They can last up to four times longer than other incandescent bulbs.
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