branch of engineering concerned with the practical applications of electricity and with devices in which the motion of electrons and other charged particles is controlled. Although electrical phenomena had attracted notice as early as the 17th century, it was not until the 19th that any strides were made to develop the study of electricity into a discipline. In that century the basic laws of electricity were mathematically formulated and the first practical applications of electricity were invented (e.g., the telephone and the incandescent lamp). Great strides have been made in electrical engineering during the 20th century, and the profession can be broadly divided into two major areashigh-power electrical engineering and low-power, or electronic, engineering. High-power electrical engineering is centred around the ability to transmit high-power currents originating in a central station along wires or cables to more remote parts where it is needed. For example, a power station may be built which can supply all the forms of energy needed in a large metropolitan area, including the energy needed for lighting and heating homes, for powering factories, and for maintaining city services. The major part of high-power electrical engineering involves the operation of power stations that use the burning of wood, coal, or oil to produce electrical energy or else make use of hydroelectric, nuclear, or geothermal energy. This power is then distributed by cables to the various centres where it is needed. In order to cope with the variations of power demand that will occur, and to cover times of breakdown and maintenance of power stations, cable networks or grids have been built so that the power need not always come from the local power station, but can be shunted from other power stations. There are three major areas of development in high-power electrical engineeringthe power converter in the power station, the means of distributing electrical power, and the means of turning the power into a form suitable for heating, lighting, operating mechanical devices, etc. In the 20th century the so-called low-current, or electronics, engineering has made extraordinary strides. One of the earliest areas of application was the telephone. The invention of the telephone was followed by the wireless telegraph and radio which enabled communication to be made by using electromagnetic waves. With further research and the development of new technology, the vacuum tube was developed, followed some years later by the semiconductor. The semiconductor supplanted the vacuum tube in radio transmission and reception and later in the amplification of audio and video signals for television. The semiconductor eventually came to be used in radar, sonar, and worldwide communications via satellite. The most widespread use of semiconductors may be in computers. The first computers were large, but as semiconductor technology improved, minicomputers and finally microcomputers were developed. The first semiconductor, the transistor, was invented in 1948; progressive miniaturization of such devices led to the development of the microchip, which can contain hundreds or thousands of transistors and other components and form a small, integrated circuit. This in turn has led to the production of highly compact and sophisticated computer devices. the branch of engineering concerned with the practical applications of electricity in all its forms, including those of the field of electronics. Electronics engineering is that branch of electrical engineering concerned with the uses of the electromagnetic spectrum and with the application of such electronic devices as integrated circuits, transistors, and vacuum tubes. In engineering practice, the distinction between electrical engineering and electronics is based on the comparative strength of the electric currents used. In this sense, electrical engineering is the branch dealing with heavy currentthat is, electric light and power systems and apparatuseswhereas electronics engineering deals with such light current applications as wire and radio communication, the stored-program electronic computer, radar, and automatic control systems. The distinction between the fields has become less sharp with technical progress. For example, in the high-voltage transmission of electric power, large arrays of electronic devices are used to convert transmission-line current at power levels in the tens of megawatts. Moreover, in the regulation and control of interconnected power systems, electronic computers are used to compute requirements much more rapidly and accurately than is possible by manual methods. Donald G. Fink Additional reading Works on the history of electrical and electronics engineering include James E. Brittain (ed.), Turning Points in American Electrical History (1977), a collection of writings on the development of electrical engineering and telecommunications in the United States; Abram John Foster, The Coming of the Electrical Age to the United States (1979), a history of electrification; Brian Bowers, A History of Electric Light and Power (1982), concentrating on electrification in Great Britain; E. Antebi, The Electronic Epoch (1982); Ernest Braun and Stuart Macdonald, Revolution in Miniature, 2nd ed. (1982), exploring the impact of semiconductor electronics in industry; Dirk Hanson, The New Alchemists (1982), a historical survey of microelectronics in industry; and H. Freitag, Electrical Engineering: The Second Century Begins (1986). Reference works on electronics engineering include Donald G. Fink and Donald Christiansen (eds.), Electronics Engineers' Handbook, 3rd ed. (1989); Stan Gibilisco and Neil Sclater (eds.), Encyclopedia of Electronics, 2nd ed. (1990); and C.H. Chen (ed.), Computer Engineering Handbook (1992). Donald G. Fink The Editors of the Encyclopdia Britannica

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