Text 3. MICHAEL FARADAY (1791-1867)

Text 1. FROM THE HISTORY OF LEARNING ELECTRICITY

1. History shows us that almost 2500 years ago, the Greeks were already familiar with the strange force which is known today as electricity. Generally speaking, three phenomena made up all of ancient people's knowledge of electrical effects. They were: the lightning flash‒a dangerous power that could kill people and burn or destroy their houses; strange yellow stones that obtained the ability of attracting light objects when they were rubbed; and the so-called electric fish, which possessed the property of growing more or less strong electric shocks. But people could neither understand their observations nor find any practical applications for them. The Greek philosopher Phales who discovered the phenomenon of amber as early as about 600 B. C. didn't know that amber was charged with electricity owing to the process of rubbing.

Electricity has been the subject of scientific interest since the early 17-th century. The first electrical engineer was probably William Gilbert (1540-1603), who designed the versorium, a device that detected the presence of statically charged objects. He drew a clear distinction between magnetism and static electricity and established the term electricity (from the Greek "electrum" which means "amber")

The famous American scientist Benjamin Franklin (1706-1790) experimented with atmospheric electricity and proved that lightning was a discharge of electricity.He invented the lightning conductor, a metal device which protected buildings from lightning by conducting the electrical charges to the earth. Franklin also proved that unlike charges are produced due to rubbing dissimilar objects. He called the charges negative and positive.

The famous Italian scientist Alessandro Volta (1745-1827) was the first to get the electric current. He constructed the voltaic pile, the first source of continuous current, a forerunner of the electric battery, in 1800. Since that time numerous scientists and inventors, Russian and foreign, havegreatly contributed to the development and practical application of electricity.

2. The first Russian electrical engineer, Academician VasiliPetrov (1761-1834) described the methods of constructing and using a battery, and discovered the effects of insulation. Petrov made the world's first discovery of the electric arc and foretold the possibility of its application for lighting purposes.

In 1820 the Danish physicist Oerstead (1777-1851) discovered the magnetic effect of the electric current.

Soon Andre Ampere (1775-1836), one of the founders of electro-dynamics, determined the difference between the current and the static charges. He investigated the connection between electricity and magnetism and proved that magnetic effect could be produced without magnets, by means electricity alone. He also created the first theory of magnetism.

 In 1825 George Ohm (1787-1854) the German physicist established the main law an electric circuit ‒ the relationship between three basic electric quantities: resistance, current and voltage in 1827.

Michael Faraday (1791-1867), an outstanding English scientist, performed more than two thousand experiments in his life time and made valuable discoveries in chemistry and physics. But his greatest discovery was the discovery of electromagnetic induction in 1831, which later became the basis all modern electrical engineering. His of dynamo machine became the forerunner of modern development of electric lightning was due to the efforts of Russian scientists and inventors. Alexander Lodygin invented the first incandescent lamp. Pavel Yablochkov improved Petrov's electric arc and invented the electric candle. He greatly contributed to the application of "Russian light" for lightning purposes. Yablochkov was the scientist in the world who used the alternating current in practiceand created the principle of the transformer. MichailDolivo-Dobrovolsky was the inventor of the generator and the wiring for the three-phase system. He showed the way to the long-distance power transmission and made electrification possible in the true sense of the word.

Text 2.ELECTRIC CURRENT

Electrical engineering is an engineering field that deals with the study and application ofelectricity and electromagnetism. Electrical engineers are usually concerned with using electricity to transmit energy. So what is electricity?

As it is known, in any metal there is a large number of free electrons of negative charge which can move through the metal under the action of an electric force. This flow of electrons is the electric current. A difference of electrical potential maintains a flow of electrons in conductor. The electric current flows through the electric circuit, a complete path, which carries a directed flow of electric charges under certain conditions. The necessary conditions mean the presence of the source of supply for an electromotive force generation and the load to which the electric current is delivered. Numerous conductors, resistors, fuses, inductance coils, throttles, capacitors, etc., are also included to the list of essential electric circuit components. The most popular circuit models are represented in electrical engineering by numerous electronic schemes, such closed and open circuits, serious and shunt circuits, linear and nonlinear installations, single-phase and polyphase systems. The schemes display the circuit components and the order of their connection.

 It should be noticed that there are different types of electric current. The current moving steadily in one direction only is a direct current (DC). The current changes its direction is called an alternating current (AC). The electrical systems in automobiles and airplanes, as well as the telegraph, telephone, the tram and special laboratories require the 90% current for their operation. But it should be noticed that about of generated at present is the alternating current. One of the great advantages of alternating current is the ease with which power at low voltage can be changed into power at high voltage and vice versa. Hence, on the one hand alternating voltage can be increased when it is necessary for long-distance energy transmission and, on the other hand, one can decrease it meet industrial requirements. Alternating current also finds wide application for lighting,heating, for operation of various devices at home and for numerous industrial purposes.

Text 3. MICHAEL FARADAY (1791-1867)

Michael Faraday, the famous English scientist, was born near London on September 22, 1791. His family was too poor to keep him in school long. At the age of 13 Michael began working as an errand boy a shop. A year later he became an apprentice to a bookbinder. Both these jobs helpedhimto develop a passionate interest in books.

Faraday was also able to attend some public lectures by the world famous chemist Sir Humphrey Davy. He attended the lectures with great enthusiasm and soon asked Davy to give him work as an assistant. Davy employed Faraday as a laboratory assistant, and Michael was very pleased to work in a scientific laboratory.

 From now on Faraday could devote practically all his time to scientific research. He made a lot of experiments, and produced several new kinds of optical glasses that greatly improved the telescope. His discovery of benzene, which he separated from oil gas, found world-wide application. He discovered the law of electrolysis, etc. But the problem of electricity and magnetism interested him above all. Faraday wanted to know if electricity could be made with the help of a magnet? First he produced a current in a wire by a magnet, then, in 1831, he showed that an electric current could induce another current in a different circuit. This discovery of the electromagnetic induction later became the basis of all modern electrical engineering.

 As it is known Faraday was one of those men who made possible the age of electricity. He measured the electric current for the first time. He also made several important observations on the conductivity of different materials. Faraday founded the theory and magnetic fields and made great contribution into the development of electro-magnetic theory of light.

 It should be noticed that all his life Faraday was poor. He believed that a scientist could not serve science for money. Although Faradayenjoyed world-wide popularity, he remained a modest man and wanted neither high titles nor prizes for his numerous discoveries.