who invented current

thomas allwa edision

From the writings of Thales of Miletus it appears that Westerners knew as long ago as 600 B.C. that amber becomes charged by rubbing. There was little real progress until the English scientist William Gilbert in 1600 described the electrification of many substances and coined the term electricity from the Greek word for amber. As a result, Gilbert is called the father of modern electricity. In 1660 Otto von Guericke invented a crude machine for producing static electricity. It was a ball of sulfur, rotated by a crank with one hand and rubbed with the other. Successors, such as Francis Hauksbee, made improvements that provided experimenters with a ready source of static electricity. Today's highly developed descendant of these early machines is the Van de Graaf generator, which is sometimes used as a particle accelerator. Robert Boyle realized that attraction and repulsion were mutual and that electric force was transmitted through a vacuum. Stephen Gray distinguished between conductors and nonconductors. C. F. Du Fay recognized two kinds of electricity, which Benjamin Franklin and Ebenezer Kinnersley of Philadelphia later named positive and negative.

Progress quickened after the Leyden jar was invented in 1745 by Pieter van Musschenbroek. The Leyden jar stored static electricity, which could be discharged all at once. In 1747 William Watson discharged a Leyden jar through a circuit, and comprehension of the current and circuit started a new field of experimentation. Henry Cavendish, by measuring the conductivity of materials (he compared the simultaneous shocks he received by discharging Leyden jars through the materials), and Charles A. Coulomb, by expressing mathematically the attraction of electrified bodies, began the quantitative study of electricity.

A new interest in current began with the invention of the battery. Luigi Galvani had noticed (1786) that a discharge of static electricity made a frog's leg jerk. Consequent experimentation produced what was a simple electron cell using the fluids of the leg as an electrolyte and the muscle as a circuit and indicator. Galvani thought the leg supplied electricity, but Alessandro Volta thought otherwise, and he built the voltaic pile, an early type of battery, as proof. Continuous current from batteries smoothed the way for the discovery of G. S. Ohm's law, relating current, voltage (electromotive force), and resistance, and of J. P. Joule's law of electrical heating. Ohm's law and the rules discovered later by G. R. Kirchhoff regarding the sum of the currents and the sum of the voltages in a circuit are the basic means of making circuit calculations.

In 1819 Hans Christian Oersted discovered that a magnetic field surrounds a current-carrying wire. Within two years André Marie Ampère had put several electromagnetic laws into mathematical form, D. F. Arago had invented the electromagnet, and Michael Faraday had devised a crude form of electric motor. Practical application of a motor had to wait 10 years, however, until Faraday (and earlier, independently, Joseph Henry) invented the electric generator with which to power the motor. A year after Faraday's laboratory approximation of the generator, Hippolyte Pixii constructed a hand-driven model. From then on engineers took over from the scientists, and a slow development followed; the first power stations were built 50 years later.

In 1873 James Clerk Maxwell had started a different path of development with equations that described the electromagnetic field, and he predicted the existence of electromagnetic waves traveling with the speed of light. Heinrich R. Hertz confirmed this prediction experimentally, and Marconi first made use of these waves in developing radio (1895). John Ambrose Fleming invented (1904) the diode rectifier vacuum tube as a detector for the Marconi radio. Three years later Lee De Forest made the diode into an amplifier by adding a third electrode, and electronics had begun. Theoretical understanding became more complete in 1897 with the discovery of the electron by J. J. Thomson. In 1910–11 Ernest R. Rutherford and his assistants learned the distribution of charge within the atom. Robert Millikan measured the charge on a single electron by 1913.

Long before any knowledge of electricity existed people were aware of shocks from electric fish. Ancient Egyptian texts dating from 2750 BC referred to these fish as the "Thunderer of the Nile", and described them as the "protectors" of all other fish. Electric fish were again reported millennia later by ancient Greek,Roman and Arabic naturalists and physicians.^[2] Several ancient writers, such as Pliny the Elder and Scribonius Largus, attested to the numbing effect ofelectric shocks delivered by catfish and torpedo rays, and knew that such shocks could travel along conducting objects.^[3] Patients suffering from ailments such as gout or headache were directed to touch electric fish in the hope that the powerful jolt might cure them.^[4] Possibly the earliest and nearest approach to the discovery of the identity of lightning, and electricity from any other source, is to be attributed to the Arabs, who before the 15th century had the Arabic word for lightning (raad) applied to the electric ray.^[5]

Ancient cultures around the Mediterranean knew that certain objects, such as rods of amber, could be rubbed with cat's fur to attract light objects like feathers.Thales of Miletos made a series of observations on static electricity around 600 BC, from which he believed that friction rendered amber magnetic, in contrast to minerals such as magnetite, which needed no rubbing.^[6]^[7] Thales was incorrect in believing the attraction was due to a magnetic effect, but later science would prove a link between magnetism and electricity. According to a controversial theory, the Parthians may have had knowledge of electroplating, based on the 1936 discovery of the Baghdad Battery, which resembles a galvanic cell, though it is uncertain whether the artifact was electrical in nature.^[8]

A half-length portrait of a bald, somewhat portly man in a three-piece suit.

Benjamin Franklin conducted extensive research on electricity in the 18th century, as documented by Joseph Priestley(1767) History and Present Status of Electricity, with whom Franklin carried on extended correspondence.

Electricity would remain little more than an intellectual curiosity for millennia until 1600, when the English scientist William Gilbert made a careful study of electricity and magnetism, distinguishing the lodestone effect from static electricity produced by rubbing amber.^[6] He coined the New Latin word electricus ("of amber" or "like amber", from ήλεκτρον [elektron], the Greek word for "amber") to refer to the property of attracting small objects after being rubbed.^[9] This association gave rise to the English words "electric" and "electricity", which made their first appearance in print in Thomas Browne's Pseudodoxia Epidemica of 1646.^[10]

Further work was conducted by Otto von Guericke, Robert Boyle, Stephen Gray and C. F. du Fay. In the 18th century, Benjamin Franklin conducted extensive research in electricity, selling his possessions to fund his work. In June 1752 he is reputed to have attached a metal key to the bottom of a dampened kite string and flown the kite in a storm-threatened sky.^[11] A succession of sparks jumping from the key to the back of his hand showed that lightning was indeed electrical in nature.^[12] He also explained the apparently paradoxical behavior of the Leyden jar as a device for storing large amounts of electrical charge.

Michael Faraday formed the foundation of electric motor technology

In 1791, Luigi Galvani published his discovery of bioelectricity, demonstrating that electricity was the medium by which nerve cells passed signals to the muscles.^[13] Alessandro Volta's battery, or voltaic pile, of 1800, made from alternating layers of zinc and copper, provided scientists with a more reliable source of electrical energy than the electrostatic machines previously used.^[13] The recognition of electromagnetism, the unity of electric and magnetic phenomena, is due to Hans Christian Ørstedand André-Marie Ampère in 1819-1820; Michael Faraday invented the electric motor in 1821, and Georg Ohm mathematically analysed the electrical circuit in 1827.^[13] Electricity and magnetism (and light) were definitively linked by James Clerk Maxwell, in particular in his "On Physical Lines of Force" in 1861 and 1862.^[14]

While it had been the early 19th century that had seen rapid progress in electrical science, the late 19th century would see the greatest progress in electrical engineering. Through such people as Nikola Tesla, Galileo Ferraris, Oliver Heaviside,Thomas Edison, Ottó Bláthy, Ányos Jedlik, Sir Charles Parsons, Joseph Swan, George Westinghouse, Ernst Werner von Siemens, Alexander Graham Bell and Lord Kelvin, electricity was turned from a scientific curiosity into an essential tool for modern life, becoming a driving force for the Second Industrial Revolution.^[15]

From the writings of Thales of Miletus it appears that Westerners knew as long ago as 600 B.C. that amber becomes charged by rubbing. There was little real progress until the English scientist William Gilbert in 1600 described the electrification of many substances and coined the term electricity from the Greek word for amber. As a result, Gilbert is called the father of modern electricity. In 1660 Otto von Guericke invented a crude machine for producing static electricity. It was a ball of sulfur, rotated by a crank with one hand and rubbed with the other. Successors, such as Francis Hauksbee, made improvements that provided experimenters with a ready source of static electricity. Today 's highly developed descendant of these early machines is the Van de Graaf generator, which is sometimes used as a particle accelerator. Robert Boyle realized that attraction and repulsion were mutual and that electric force was transmitted through a vacuum. Stephen Gray distinguished between conductors and nonconductors. C. F. Du Fay recognized two kinds of electricity, which Benjamin Franklin and Ebenezer Kinnersley of Philadelphia later named positive and negative.

A new interest in current began with the invention of the battery. Luigi Galvani had noticed (1786) that a discharge of static electricity made a frog 's leg jerk. Consequent experimentation produced what was a simple electron cell using the fluids of the leg as an electrolyte and the muscle as a circuit and indicator. Galvani thought the leg supplied electricity, but Alessandro Volta thought otherwise, and he built the voltaic pile, an early type of battery, as proof. Continuous current from batteries smoothed the way for the discovery of G. S. Ohm 's law, relating current, voltage (electromotive force), and resistance, and of J. P. Joule 's law of electrical heating. Ohm 's law and the rules discovered later by G. R. Kirchhoff regarding the sum of the currents and the sum of the voltages in a circuit are the basic means of making circuit calculations.

In 1819 Hans Christian Oersted discovered that a magnetic field surrounds a current-carrying wire. Within two years André Marie Ampère had put several electromagnetic laws into mathematical form, D. F. Arago had invented the electromagnet, and Michael Faraday had devised a crude form of electric motor. Practical application of a motor had to wait 10 years, however, until Faraday (and earlier, independently, Joseph Henry) invented the electric generator with which to power the motor. A year after Faraday 's laboratory approximation of the generator, Hippolyte Pixii constructed a hand-driven model. From then on engineers took over from the scientists, and a slow development followed; the first power stations were built 50 years later.

In 1873 James Clerk Maxwell had started a different path of development with equations that described the electromagnetic field, and he predicted the existence of electromagnetic waves traveling with the speed of light. Heinrich R. Hertz confirmed this prediction experimentally, and Marconi first made use of these waves in developing radio (1895). John Ambrose Fleming invented (1904) the diode rectifier vacuum tube as a detector for the Marconi radio. Three years later Lee De Forest made the diode into an amplifier by adding a third electrode, and electronics had begun. Theoretical understanding became more complete in 1897 with the discovery of the electron by J. J. Thomson. In 191011 Ernest R. Rutherford and his assistants learned the distribution of charge within the atom. Robert Millikan measured the charge on a single electron by 1913