AN ARTICLE ON BRIEF HISTORY OF CHARGING A BODY-ELECTROSTATICS:
Ancient-Greeks:
 |
| fig. Discovery of charge. |
Ancient-Greeks:
The 1st reference to the study of electricity begins with the ancient Greek philosophers who new that amber, when rubbed attracted certain light bodies. However, no theories were constructed from their observations.
William Gilbert (1544-1603):
A well known physician-William Gilbert, wrote extensively on the topic of magnetism and electricity.He named it as "amber effect" electricity, since amber in Greek is known as "electron." Gilbert experiment that there were other bodies that could be come electrified similar to amber. He also called these bodies electrics. (we call these bodies insulators). Gilbert emphasized the fact that electricity was different form magnetism because:
Stephen Gray (1666-1736):
Stephen Gray was inspired by Hauksbee's experiments, try to transmit the power of attraction. Through chance of observation he noticed that sometimes an electrified glass tube stopped with a cork attracted a feather not to glass but to the stopper. After confirming the communication of electricity through several materials, Stephen Gray determined that the "electric virtue" could be carried (transmitted) over long distances. His most famous experiment was with a boy suspended horizontally by two hairlines and hooks fixed at the ceiling.When an electrified tube was held near his foot, pieces of metal foil were attracted to his face and to outstretched hands.This was called the Flying Boy experiment.
Jean Desaguliers (1683-1744):
Luigi and Alessandro Volta each made two very most important discoveries that helped the scientific community make a transition from static electricity to direct current electricity (electricity in motion). In fact these two scientists had what is probably the longest and most heated debate in the history of science. By the 18th. century it had been generally accepted that muscles move by means of a special "nervous fluid," which originates in the brain and travels through the nerves. Work done on a few species of fish, (the torpedo, found in the Mediterranean; gymnotus electrics, the electric eel), seemed to supported this idea. Legend has it that Galvani had prepared frog legs to make a soup for his sick wife and noticed that the legs contracted every time when an electrical machine working nearby produced a spark. After completing several experiments, Galvani published, in 1791, a paper on his new theory of 'Animal Electricity'. In the paper Galvani observed that when the nerve of a prepared frog's leg is touched with one metal and the muscle is touched with another metal a strong contraction of the muscle is observed. The cause of this contraction, he thought was due to the flow of electricity from the nerve to the muscle. At first this paper was well received, but within a year much of the scientific community had polarized into two factions. Those supporting Galvani's theory and those supporting Volta's theory of contact electricity, which simply put, is that when two different metals are placed in contact electricity flows from one to the other. This debate continued until 1800 when Volta released information on his new discovery of the Voltaic pile. The debate did not die out altogether; the emphasis shifted to studying the effects of Volta's new apparatus. Volta's first pile consisted of alternating zinc and silver disks (he used silver coins) separated by a wet cloth or card. To test other physiological effects Volta adapted his pile so that the metals were connected via cups, (Crown of Cups), filled with water or other conducting fluid. Volta's pile became the first electrical source of a continuous action, which did not involve any mechanical work such as the electrical machines. The pile was thus the predecessor to the electrochemical cell or better known today as the battery.
Producers of Static Electricity
William Gilbert (1544-1603):
A well known physician-William Gilbert, wrote extensively on the topic of magnetism and electricity.He named it as "amber effect" electricity, since amber in Greek is known as "electron." Gilbert experiment that there were other bodies that could be come electrified similar to amber. He also called these bodies electrics. (we call these bodies insulators). Gilbert emphasized the fact that electricity was different form magnetism because:
- Lodestone(naturally occurring magnets)-attracts only iron, while electrics also attract many kinds of bodies.
- Unlike electrics-lodestone acts though other substances.
- while an electric draws other bodies to every part of it.Lodestone attracts to its poles.
The following experiment contained his rule: A piece of metal foil suspended near an electrified tube is first attracted to it, but after obtaining some electricity it recedes from the tube. If on its way back the foil touches next body it loses electricity and is again attracted by the tube.Charles Dufay discovered that there were two types of electricity. He named it as "vitreous" (glass, precious stones) and "resinous" (amber, sealing wax, silk).
Robert Boyle (1627-1691):
Robert Boyle showed that "amber" retained its attracting power in a glass vessel. After air was pumped out and concluded that the air was not the cause of attraction.
Otto von Guericke (1601-1674):
Otto von Guricke, mayor of Magdeburg, experiment with a sulphur globe, obtain it by melting sulphur in a glass glove and breaking the glass. He mounted globe upon axis and rotated it in a wooden frame rubbing the globe with his hand.The purpose of Otto's globe was to model the earth with all its "mundane virtues".
- Attraction.
- Repulsion.
Fire,Smoke and the moon, among several others. Some people had trouble duplicating his experiment because they did not have hands as rough as Guericke and could not produce the frictional static electricity required to suspend feathers and other objects as Guericke could. Thus other people thought of Otto von Guericke as a magician or mystical leader.
Francis Hauksbee (1688-1763):
Francis Hauksbee was the demonstrator of the Royal Society. His one of the most famous experiments were on producing light by friction.Light appeared both outside and inside of the evacuated rotating glass globe when rubbed with a hand. Francis Hauksbee also found that an electrified globe could excite light in another globe, when it was placed either inside or outside the former.
Stephen Gray (1666-1736):
Stephen Gray was inspired by Hauksbee's experiments, try to transmit the power of attraction. Through chance of observation he noticed that sometimes an electrified glass tube stopped with a cork attracted a feather not to glass but to the stopper. After confirming the communication of electricity through several materials, Stephen Gray determined that the "electric virtue" could be carried (transmitted) over long distances. His most famous experiment was with a boy suspended horizontally by two hairlines and hooks fixed at the ceiling.When an electrified tube was held near his foot, pieces of metal foil were attracted to his face and to outstretched hands.This was called the Flying Boy experiment.
Charles-Francois Dufay (1698-1739) French:
Charles-Frencois Dufay was the first to make any theoretical generalizations from his experiments. He was inspired in 1732, at age 25, by reading Stephen Gray's papers and in 1733 he derived the following rule:"an electrified body attracts neutral objects and repels the electrified ones".
Jean Desaguliers (1683-1744):
Jean Desaguliers, a demonstrator for the Royal Society, made the 1st generalizations of the two kinds of electricity.
- A body electrical per se, is such a body in which one may excite electricity by rubbing, hammering, melting, warming, patting, hammering, melting, warming, or any other action on the body itself.
- A non-electric, such a body cannot be made electrical by any action upon the body itself immediately, though it is capable of receiving the virtue (electricity) from an electric. Non-electrics were called conductors by Desaguliers. This sounds like a contradiction in terms but if you realize that a piece of metal cannot be electrified by rubbing .
Georg Bose (1710-1761) German:
George Bose, a Professor of Natural Philosophy was the first to make widespread use of an electrical machine invented by Hauksbee in 1709 at Wittenberg. He found that electrical experiments could be performed easily by using the Hauksbee machine. The most important improvement to Hauksbee's machine was Bose addition of a prime conductor. A long metal body placed near the rotating globe and insulated from the ground. When the prime conductor was electrified by the globe and touched by a person, a spark was produced. The machine was brought to England in 1746 by William Watson 1715-1787, an apothecary and a member of the Royal Society.
Johann Winkler (1703-1770):
Johan Winkler, professor of Languages at Leipzig, improved on the Globe electrical machine by adding a cushion to rub the globe. In 1740's cylinder machines appeared and gradually replaced the globe machines. These machines had a prime conductor provided with different points. These points were directed to a rotating cylinder and speed up the process of electrification.
John Cuthbertson English:
The 1st plate machines appeared in the 1780's. The most powerful 18th century machine was built by John Cutheberson, and English instrument maker. This machine, with twin plates 5 feet in diameter, installed in Haarlem Holland, could produce a spark 2 feet long and as thick as a quill pen.
Ewald Jurgen von Kleist (1700-1748):
Ewald Jurgen von Kleist was the dean of a cathedral in Pomerania, in November 1745 , put a nail into a small medicine bottle and electrified it with an electrical machine.When he touched nail with his hand he received a strong shock in his arms and shoulder. He was able to ignite a spirit of wine, but the only when the jar was held in hand. Kleist immediately informed several scientists of this discovery but his account was not very specific and they failed to repeat his experiments. After receiving better instructions Daniel Gralath from 1708 to 1767, the mayor of Danzig, succeeded. A same experiment was performed in March 1746 by Pieter van Musschenbroek, (1692-1761), professor at the University of Leyden. Andreas Cunaeus (1712-1788), a lawyer, held the jar in hand instead of placing it on a table and made an interesting improvement of covering the jar with a conductor. He reported his experiment to Jean Allemand (1713-1787), a collegue of Muschenbroek, who repeated it successfully with a beer glass. He says the discharge- "Knocked the wind out of me for several minutes." Allemand, in a letter to the Paris Academy of Sciences stated, "I would like to tell you about a new but terrible experiment, which I advise you never to try yourself, nor would I, who experienced it and survived by the grace of God, not again for all the kingdom of France." Soon after the report was made many scientists repeated the experiment, (never tell someone not to do something). One of the scientists, Louis-Guilliaume Le Monnier (1717-1799), professor of Botany in Paris, discharged a Leyden jar through a chain of 140 courtiers in the presence of the King of France. In next experiment, a shock was transmitted 2.5 miles away through a chain of people holding iron wires.
Luigi Galvani (1737-1798):
Luigi and Alessandro Volta each made two very most important discoveries that helped the scientific community make a transition from static electricity to direct current electricity (electricity in motion). In fact these two scientists had what is probably the longest and most heated debate in the history of science. By the 18th. century it had been generally accepted that muscles move by means of a special "nervous fluid," which originates in the brain and travels through the nerves. Work done on a few species of fish, (the torpedo, found in the Mediterranean; gymnotus electrics, the electric eel), seemed to supported this idea. Legend has it that Galvani had prepared frog legs to make a soup for his sick wife and noticed that the legs contracted every time when an electrical machine working nearby produced a spark. After completing several experiments, Galvani published, in 1791, a paper on his new theory of 'Animal Electricity'. In the paper Galvani observed that when the nerve of a prepared frog's leg is touched with one metal and the muscle is touched with another metal a strong contraction of the muscle is observed. The cause of this contraction, he thought was due to the flow of electricity from the nerve to the muscle. At first this paper was well received, but within a year much of the scientific community had polarized into two factions. Those supporting Galvani's theory and those supporting Volta's theory of contact electricity, which simply put, is that when two different metals are placed in contact electricity flows from one to the other. This debate continued until 1800 when Volta released information on his new discovery of the Voltaic pile. The debate did not die out altogether; the emphasis shifted to studying the effects of Volta's new apparatus. Volta's first pile consisted of alternating zinc and silver disks (he used silver coins) separated by a wet cloth or card. To test other physiological effects Volta adapted his pile so that the metals were connected via cups, (Crown of Cups), filled with water or other conducting fluid. Volta's pile became the first electrical source of a continuous action, which did not involve any mechanical work such as the electrical machines. The pile was thus the predecessor to the electrochemical cell or better known today as the battery.
Detectors of Electricity:
Versorium: By William Gilbert was a long and narrow body, such as a broomstick or aluminum pipe, suspended at the center of gravity.
Electrometer:
The simplest and most sensitive detector of electricity is a thin thread of cotton about 5-10 cm. long suspended so that it can move freely and is insulated from the ground. Stephen Gray in 1729, was the first to notice that the angle the thread made with the vertical direction increased with the quantity of electricity on the body. In 1734, Jean Antoine Nollet built an electrometer of two threads hanging side by side. When an electrified body approached them, the threads, having been charged with electricity of the same sign, diverged, making an angle proportional to the charge. In 1753, John Canton attached balls of cork or elder pith to the threads. William Henly, in 1770, built a quadrant electrometer in which the thread was replaced by a light rod loaded with a cork ball. The best of them were Tiverius Cavallo's electrometer with fine silver wires supporting conical pieces of cork (1777), Alessandro Volta's condenser electrometer (1780), and the gold-leaf electrometer of Abraham Bennet (1789). Bennet was able to detect such weak charges as those due to evaporation of water.
Producers of Static Electricity
Electrical Machines:
In the 1740's cylinder machines appeared and gradually replaced the globe machines. These machines had a prime conductor provided with several points. The points were directed to a rotating cylinder and speeded up the process of electrization. The main advantages to the cylinder generator over the globe generator was their ability to produce a consistent charge throughout the whole cylinder and to transfer that charge more uniformly to the prime conductor. The main disadvantage to the globe and cylinder generators was that as they were rubbed the air inside would expand causing the cylinders or globes to explode, injuring operators and spectators. Thus during the next 10 to 15 years the plate generator was introduced.
It is not specifically known who built the first plate generator. However, the first to make extensive use of it was Jesse Ramsden, a well known and respected instrument maker. The plate machine was also used in the medical profession after another instrument maker, John Cuthbertson was able to produce a plate machine so portable that it could be carried by a doctor making house calls. Some of the reported medical cures obtained by use of the electrostatic generator included servicing obstructions (constipation), curing nervous disorders, headaches, toothaches due to colds, deafness from too much earwax and even in rare cases curing blindness. (An amazing medical tool!)
Electrophorus:
During the 1750's Benjamin Franklin, Johann Carl Wilcke, John Canton, and Franz Ulrich Theodor Aepinus discovered and explained the important phenomenon of electrization through induction. Soon After this discovery Alessandro Volta invented the electrophorus in 1775. The electrophorus consisted of an insulator and a metal plate attached to an insulating handle. Volta found that once the electrophorus was initially electrified the top plate could continue to produce electricity, a perpetual source of electricity.
No comments:
Post a Comment