Answers about Electrical Wiring > 커뮤니티 카카오소프트 홈페이지 방문을 환영합니다.

It will protect itself. A brief review of some of the European systems that have been constructed will convince us of this. The present European system dates from 1875. The cable is similar to that used for submarine purposes. In answer, I propose to describe briefly what has been done in this direction in European cities, then to look at some experiments lately made in this country, and thus to show how far such a plan is and how far it is not practicable. Look for it in your owner's manual. Morse proclaimed his faith in it as early as the year 1840, and in 1842 he submerged a wire, insulated with tarred hemp and india-rubber, in the water of New York harbour, what is electric cable and telegraphed through it. The cable most generally made in Paris consists of seven gutta-percha-covered wires laid into a cable covered with tarred hemp and drawn into a lead pipe; this pipe is fastened by hooks to the side-wall of the sewer. Many miles of this cable were laid, some with the lead pipe laid directly in the earth, some with it drawn again into iron pipes, and some carried through the sewers of the principal cities.

Conversation over these lines is not so easily carried on as by means of overhead wires, and it is frequently possible to overhear other conversation. Instead of a single wire for each circuit, two wires twisted together are used, the current going out over one and returning over the other. The cables, of which several kinds are in use, run out from the basement of the central office through these pipes and up the side of buildings to roofs, from which they spread out to the subscribers by means of ordinary overhead lines. Congress directed that FM be the means of voice transmission for television. At more temperate places the ordinary means of drying the air by taking advantage of the absorbing power of sulphuric acid for moisture prevailed. But an excess of moisture in the air diminishes the available supply of exalted electricity. The paper was followed by others on the mathematical theory of electricity; and in 1845 he gave the first mathematical development of Faraday's notion, that electric induction takes place through an intervening medium, or 'dielectric,' and not by some incomprehensible 'action at a distance.' He also devised an hypothesis of electrical images, which became a powerful agent in solving problems of electrostatics, or the science which deals with the forces of electricity at rest.

The distances within this city are so short that neither induction nor retardation has to be considered in the telegraph wires. Are computer monitors radioactive? What are the different Personal Computer hardware components and their functions? These types of cables are used for computer networking and audio-video networking. There are these types of cables which transport optical data signals from an attached light source to the receiving device. At a receiving station the current coming in from the cable has simply to be passed through the coil of the 'speaker' before it is sent into the ground, and the wandering light spot on the screen faithfully represents all its variations to the clerk, who, looking on, interprets these, and cries out the message word by word. The number and type of protective layers surrounding the core depends upon the use for which the cable is intended. It consists of seven copper wires, each coated with two layers of gutta-percha and two of Chatterton's compound, and the whole covered with an armor of galvanized-iron wires. Four copper wires were each wound with cotton, soaked in shellac, and the whole drawn into a lead tube. It has two or more insulated copper wires which are twisted with each other and are colour-coded.

In the German cities we have seen that many of the telegraph-wires are carried under-ground from the center of the city to connect with cables running to other cities. In Vienna, Prague, Brünn, Munich, Augsburg, Nuremberg, and many other cities, the telegraph-wires are carried under-ground by armored cables to the outside of the city. In London, the telegraph wires are carried from the central office to many of the branch offices and to the railways leading out of the city under-ground. The cost of the piping and chambers is in round numbers $50,000 per mile, and these pipes are intended to accommodate one thousand wires. There are several thousand miles of wire in the sewers of Paris, and the cost of the gutta-percha-covered cables is about $140 per mile of wire, or about five times the cost of a pole line to do the same work. The telephone wires are in Paris protected from these evils by an extremely simple though expensive device. How to choose electrical wires and cables? The paraffined cables are, however, considerably cheaper, though their durability has not yet been proved. Hardly was the section completed, however, when water found its way into the joints, destroying the insulation, and the conductors failed.