History of Electricity
While it is true that we are not certain when the electricity originated, it is no less true that we have reference to the year 600 BC, the Greek philosopher TALES DE MILETO rubbed a rod of amber with a wool or skin, loads were obtained that attracted small Objects, and rubbing a lot of time could cause the appearance of a spark; However, it was the Greek philosopher THEOPHRASTUS (374-287 BC), the first to establish in a treaty that other substances have this same power, thus leaving a record of the first scientific study on electricity
Near the ancient Greek city of Magnesia were the so-called Magnesia stones, which included magnetite. The ancient Greeks observed that the pieces of this material were attracted to each other, and also to small iron objects. The words magneto (magnet) and magnetism derive from these words.
In 1600: Queen Elizabeth I orders the Royal Physicist William Gilbert (1544-1603) to study the magnets to improve the accuracy of the compasses used in navigation, this being the main basis for the definition of the fundamentals of electrostatics and magnetism; Gilbert was the first to apply the term Electricity of the Greek "elektron" = amber. Gilbert is the unit of measurement of the driving magnet force.
In 1752, Benjamin Franklin (1706-1790) demonstrated the electric nature of the rays. Developing the theory that electricity is a fluid that exists in matter and its flow is due to the excess or defect of the same in it. I invented the lightning rod. In 1780 he invented Bifocal lenses.
In 1776, Charles Augustine de Coulomb (1736-1806) invented the torsion balance with which he accurately measured the force between the electric charges and corroborated that the force was proportional to the product of the individual charges and inversely proportional to the square of the Distance separating them. Coulomb is the unit of measurement of Electric Charge.
In 1800, Alejandro Volta (1745-1827) built the first electrostatic cell and the battery capable of producing electric current. His inspiration came from the study by the Italian Physicist Luigi Galvani (1737-1798) about the nervous-electric currents in the frog legs. Galvani proposed the theory of Animal Electricity, which contradicted Volta, who believed that muscle contractions were the result of the contact of the two metals with the muscle. His subsequent investigations allowed him to elaborate a chemical cell capable of producing continuous current that is how the Pila developed. Volts is the unit of measurement of the electrical potential (Voltage).
From 1801 to 1815, Sir Humphry Davy (1778-1829) developed electrochemistry (name assigned by himself), exploring the use of Volta's battery, and trying to understand how it works. In 1801 he observed the electric arc and incandescence in a conductor energized with a battery. Between 1806 and 1808 he published the results of his research on electrolysis, where he achieved the separation of Magnesium, Barium, Strontium, Calcium, Sodium, Potassium and Boron. In 1807 he makes a stack with more than 2000 double plates, with which he discovers Chlorine and shows that it is an element, instead of an acid. In 1815 he invented the safety lamp for the miners. Without a doubt, the most important discovery is made that year, when he discovers the young Michael Faraday and takes him as an assistant.
In 1819, Danish scientist Hans Christian Oersted (1777-1851) discovers electromagnetism, when in an experiment for his students, the compass needle accidentally placed near a cable energized by a voltaic cell, moved. This discovery was crucial in the development of Electricity, as it highlighted the relationship between electricity and magnetism. Oersted is the unit of measure of Magnetic Reluctance.
In 1823, Andre-Marie Ampere (1775-1836) established the principles of electrodynamics, when he came to the conclusion that the electromotive force is a product of two effects: electric voltage and electric current. Experiment with conductors, determining that they attract each other if currents flow in the same direction, and repel each other when they flow against each other. Ampere produces an excellent mathematical result of the phenomena studied by Oersted. Ampere is the unit of measurement of the electric current.
In 1826, the German physicist Georg Simon Ohm (1789-1854) was the one who accurately formulated the law of electric currents, defining the exact relationship between voltage and current. Since then, this law has been known as Ohm's law. Ohm is the unit of measure of the Electrical Resistance.
In 1831, Michael Faraday (1791-1867) at age 14 worked as a bookbinder, which allowed him to have the time to read and develop his interest in Physics and Chemistry. In spite of its low formal preparation, it took a fundamental step
24 March of 2017
They are materials whose resistance to the passage of electricity is very low. The best electrical conductors are metals, such as copper, gold, iron, silver and aluminum, and their alloys, although there are other nonmetallic materials that also possess the property of conducting electricity, such as graphite or dissolutions, and Saline solutions (eg, seawater) or any material in a plasma state.
For the transportation of electrical energy, as well as for any installation of domestic or industrial use, the best conductor is copper (in the form of cables of one or several wires). Although silver is the best driver, but because of its high price is not used so often. It is also possible to use aluminum, which although it has an electrical conductivity of 60% of the copper, is nevertheless a material three times lighter, so its use is more indicated in airlines than in the transmission Of electricity in high voltage networks.1 Unlike what most people believe, gold is slightly worse conductive than copper; However, it is used in battery terminals and electrical connectors because of its durability and "resistance" to corrosion.
The electrical conductivity of pure copper was adopted by the International Electrotechnical Commission in 1913 as the standard reference for this magnitude, establishing the International Annealed Copper Standard or IACS. According to this definition, the conductivity of the annealed copper measured at 20 ° C is equal to 58.0 MS / m.2 This value is what is called 100% IACS and the conductivity of the rest of the materials is expressed as a certain percentage of IACS. Most metals have conductivity values below 100% IACS but there are exceptions such as silver or the very high conductivity special copper designated C-103 and C-110.3
Due to the excellent conductivity of this material, or aluminum that although it has lower conductivity is more economical. Generally it has insulation in which it will depend on the working voltage level, the nominal current, the ambient temperature and the operating temperature of the conductor. An electrical cable consists of: