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Devices
DEVICES:
Leyden Jar - This device was used by early experimenters to store electric energy from static electric sources. The term "condensor" orginated with leyden jars and was created because people believed electricity was a fluid that could be condensed into the leyden jars. In modern times we have a greater understanding of the mechanics of electricity and with that the term "capasitor" was adopted. In its most basic form the Leyden jar is a cylindrical container, of such material as glass or plastic, with a layer of metal foil on the inside and on the outside. Once the outside foil is grounded the inside foil aquires a charge of equal and opisite force. If a charge is given to the outer foil over an extended period of time then the charge of the inner foil becomes greater. This inner charge can then be discharged in one shock that is a combinations of all previos shocks given to the leyden jar.
http://www.alaska.net/~natnkell/leyden.htm
Voltaic Pile-This voltaic pile consists of thirty metal disks separated by layers of (dampened) cloth. During the first part of the nineteenth century large voltaic piles were constructed to provide sources of continuous current. Volta demonstrated the actions of piles such as the one shown to Napoleon who was reportedly quite impressed. Bonaparte, incidentally, was very partial to scientists; in 1813 he allowed free passage to Davy and Faraday to visit Ampère in Paris despite the hostilities between England and France.
http://www.ece.umd.edu/~taylor/volta.htm
Dynamo- As its name suggests, a generator generates electricity. Michael Faraday’s discovery of electromagnetic induction demonstrated a way to construct a simple generator, but there was little need for such a device until commercial technologies that used electricity, such as lights, appeared. The earliest commercial uses of electricity, such as telegraphy, arc lighting systems, and metal electroplating used batteries as their power source. This was a very expensive way of generating electricity.
In the 1860s and 1870s many inventors sought ways of using Faraday’s induction principle to generate electricity mechanically. Two kinds of generators emerged. The first type was a generator of direct current (DC) electricity. The second type was a generator of alternating current (AC) electricity. In truth, a DC generator could generate AC current, but it contains a simple device called a commutator to turn AC into DC. A commutator reroutes the flow of electrons inside the DC generator, so that the energy that appears at the output is a pulsing direct flow. An AC generator does not need a commutator and generates AC directly. One of the most important inventors of generators was German Werner von Siemens, who designed improved DC generators and called them dynamos. An even better generator was introduced by Zenobe Gramme in 1867. Gramme’s dynamos generated AC current and were widely used in arc lighting systems. In 1872, however, von Siemens reemerged and invented what is essentially the modern type of dynamo, referred to as the drum armature type of machine, which was a more efficient design. AC and DC generators were both used from the 1870s on. For example, AC generators were used in a type of outdoor arc lighting known as the Jablochkoff Candle. However, in the late 1870s when Thomas Edison devised his highly successful electric lighting system, he used DC generators. A major reason for this choice was that Edison wanted to use electric power both for lighting (for which AC was fine) and for running electric motors. At the time, there was no good AC electric motor available, so DC was the only option. In 1882 Edison installed DC generators at the Pearl Street station facilities in New York City, one of the earliest commercial power generating plants. As electric lighting and centrally distributed power began to achieve commercial success in the 1880s, inventors began looking for ways to distribute central-station power over longer distances. Edison’s DC system was poorly adapted to this, because he had chosen to use 120-volt bulbs and motors. A much higher voltage would have been easier to transmit down long wires, because at a low voltage much energy is lost as heat. Edison stations, such as that at Pearl Street, could be no more than about a mile from the customer. AC offered an alternative: a way to generate at a low voltage, “step up” the voltage for transmission using a simple device called a transformer, and then “step down” the voltage at the customer premises. The only remaining problem, though, was the lack of a suitable AC motor design. Nikola Tesla, a Serbian immigrant to the United States, devised an improved AC generator as well as a practical AC motor. Tesla’s system used polyphase AC, in which the generator generated several different AC flows that were combined or superimposed onto one another to create a single polyphase AC output, with the component currents “out of phase” with one another. The Tesla motor, introduced in 1887, was designed so that the peaks of this polyphase current supplied power at just the right moment in the rotation of the motor, and the resulting induction motor as he called it, ran smoothly. With a practical AC motor and generator in hand, along with transformers to raise and lower voltage, Tesla’s system could be used by power companies to create ever-larger networks of power distribution using massive power plants, such as the Niagara Falls hydroelectric plant built in the 1890s. Larger power systems helped lower costs, which stimulated demand for electricity, especially in homes.
http://ieee-virtual-museum.org/collection/tech.php?taid=&id=2345846&lid=1
transformer- A transformer is a device used to change the voltage of electric power. Power plants generate power at a low voltage, but power needs to be at a very high voltage for the long trips down the wires from the generator to your house. But at your house the voltage of the power has to drop back down again so that it won’t be dangerous and so your appliances aren’t blown out. A transformer allows the power to change voltages from place to place.
In 1831 Michael Faraday discovered the principles that make transformers possible. Using an induction ring Faraday discovered that an electric current flowing through one wire could have the effect of creating or “inducing” an identical current in a nearby wire. This only happens when the voltage is changing—such as when the power is snapped on and the voltage rises from 0 to its peak. The reason for the induction of a current in a nearby wire is that every flow of current in a wire results in the creation of a magnetic field around the wire. A second wire placed nearby, within that field, is influenced by the magnetism. As the field expands or collapses, it acts on the electrons in the second wire and creates a new flow of current. Winding the wire into coils makes the device more compact, and wrapping the coils onto an iron bar or ring concentrates the magnetic field in a small area. We use the name transformer because it is used in alternating current systems to raise or lower voltages. Alternating current creates a fluctuating magnetic field as it flows in a wire. If the number of turns in the first coil is lower than in the second, then higher voltage will be induced in the second coil. If the first coil has many turns, then the “secondary” voltage will be lower. Electric power systems use this principle to raise the voltage produced by a generator or dynamo to a high level, such as 100,000 volts or higher. At this high voltage, electricity can travel hundreds of miles along transmission wires without being significantly diminished. Near your home, another transformer does just the opposite—it lowers the voltage back down to 120 volts in the United States (220 volts in Europe) so that you can use it.
http://ieee-virtual-museum.org/collection/tech.php?taid=&id=2345816&lid=1
electric motor (AC & DC)-
A simple motor has six parts, as shown in the diagram below:
arc light- Electric light that uses the illumination of an electric arc maintained between two electrodes. The English chemist Humphry Davy demonstrated the electric arc in 1802 and electric arc lighting was first introduced by English electrical engineer W E Staite in 1846. The lamp consists of two carbon electrodes, between which a very high voltage is maintained. Electric current arcs (jumps) between the two electrodes, creating a brilliant light. Its main use in recent years has been in cinema projectors.
http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0016408.html
incandescent bulb-Incandescent light bulbs, such as those we commonly use in our homes, involve heating a very fine filament of wire - usually tungsten - to a high temperature, at which point the wire gives off a very bright light. The material used should have a significant intrinsic electrical resistance. Simple application of a high voltage to a very thin wire then causes intense heating in the wire and a very bright light results. The wire must be enclosed in a sealed, inert environment. All air is removed from the bulb and an inert gas such as argon is introduced to prevent the tungsten simply reacting with oxygen and catching fire. The tungsten is thus unaffected by the process which can be continued indefinitely. The main cause of failure of tungsten filament lamps is the speed of heating and cooling when the lamp is switched on and off. This results in thermal fatigue - the wire breaks because of repeated expansion and contraction and the bulb fails.
http://www.btinternet.com/~k.trethewey/incandescant_light_bulb.htm
diode-A diode is a semiconductor device which allows current to flow through it in only one direction. Although a transistor is also a semiconductor device, it does not operate the way a diode does. A diode is specifically made to allow current to flow through it in only one direction.
http://www.interq.or.jp/japan/se-inoue/e_diode.htm
transistor-The transistor is a three terminal, solid state electronic device. In a three terminal device we can control electric current or voltage between two of the terminals by applying an electric current or voltage to the third terminal. This three terminal character of the transistor is what allows us to make an amplifier for electrical signals, like the one in our radio. With the three-terminal transistor we can also make an electric switch, which can be controlled by another electrical switch. By cascading these switches (switches that control switches that control switches, etc.) we can build up very complicated logic circuits. These logic circuits can be built very compact on a silicon chip with 1,000,000 transistors per square centimeter. We can turn them on and off very rapidly by switching every 0.000000001 seconds. Such logic chips are at the heart of your personal computer and many other gadgets you use today.
http://nobelprize.org/educational_games/physics/transistor/history/
Leyden Jar - This device was used by early experimenters to store electric energy from static electric sources. The term "condensor" orginated with leyden jars and was created because people believed electricity was a fluid that could be condensed into the leyden jars. In modern times we have a greater understanding of the mechanics of electricity and with that the term "capasitor" was adopted. In its most basic form the Leyden jar is a cylindrical container, of such material as glass or plastic, with a layer of metal foil on the inside and on the outside. Once the outside foil is grounded the inside foil aquires a charge of equal and opisite force. If a charge is given to the outer foil over an extended period of time then the charge of the inner foil becomes greater. This inner charge can then be discharged in one shock that is a combinations of all previos shocks given to the leyden jar.
http://www.alaska.net/~natnkell/leyden.htm
Voltaic Pile-This voltaic pile consists of thirty metal disks separated by layers of (dampened) cloth. During the first part of the nineteenth century large voltaic piles were constructed to provide sources of continuous current. Volta demonstrated the actions of piles such as the one shown to Napoleon who was reportedly quite impressed. Bonaparte, incidentally, was very partial to scientists; in 1813 he allowed free passage to Davy and Faraday to visit Ampère in Paris despite the hostilities between England and France.
http://www.ece.umd.edu/~taylor/volta.htm
Dynamo- As its name suggests, a generator generates electricity. Michael Faraday’s discovery of electromagnetic induction demonstrated a way to construct a simple generator, but there was little need for such a device until commercial technologies that used electricity, such as lights, appeared. The earliest commercial uses of electricity, such as telegraphy, arc lighting systems, and metal electroplating used batteries as their power source. This was a very expensive way of generating electricity.
In the 1860s and 1870s many inventors sought ways of using Faraday’s induction principle to generate electricity mechanically. Two kinds of generators emerged. The first type was a generator of direct current (DC) electricity. The second type was a generator of alternating current (AC) electricity. In truth, a DC generator could generate AC current, but it contains a simple device called a commutator to turn AC into DC. A commutator reroutes the flow of electrons inside the DC generator, so that the energy that appears at the output is a pulsing direct flow. An AC generator does not need a commutator and generates AC directly. One of the most important inventors of generators was German Werner von Siemens, who designed improved DC generators and called them dynamos. An even better generator was introduced by Zenobe Gramme in 1867. Gramme’s dynamos generated AC current and were widely used in arc lighting systems. In 1872, however, von Siemens reemerged and invented what is essentially the modern type of dynamo, referred to as the drum armature type of machine, which was a more efficient design. AC and DC generators were both used from the 1870s on. For example, AC generators were used in a type of outdoor arc lighting known as the Jablochkoff Candle. However, in the late 1870s when Thomas Edison devised his highly successful electric lighting system, he used DC generators. A major reason for this choice was that Edison wanted to use electric power both for lighting (for which AC was fine) and for running electric motors. At the time, there was no good AC electric motor available, so DC was the only option. In 1882 Edison installed DC generators at the Pearl Street station facilities in New York City, one of the earliest commercial power generating plants. As electric lighting and centrally distributed power began to achieve commercial success in the 1880s, inventors began looking for ways to distribute central-station power over longer distances. Edison’s DC system was poorly adapted to this, because he had chosen to use 120-volt bulbs and motors. A much higher voltage would have been easier to transmit down long wires, because at a low voltage much energy is lost as heat. Edison stations, such as that at Pearl Street, could be no more than about a mile from the customer. AC offered an alternative: a way to generate at a low voltage, “step up” the voltage for transmission using a simple device called a transformer, and then “step down” the voltage at the customer premises. The only remaining problem, though, was the lack of a suitable AC motor design. Nikola Tesla, a Serbian immigrant to the United States, devised an improved AC generator as well as a practical AC motor. Tesla’s system used polyphase AC, in which the generator generated several different AC flows that were combined or superimposed onto one another to create a single polyphase AC output, with the component currents “out of phase” with one another. The Tesla motor, introduced in 1887, was designed so that the peaks of this polyphase current supplied power at just the right moment in the rotation of the motor, and the resulting induction motor as he called it, ran smoothly. With a practical AC motor and generator in hand, along with transformers to raise and lower voltage, Tesla’s system could be used by power companies to create ever-larger networks of power distribution using massive power plants, such as the Niagara Falls hydroelectric plant built in the 1890s. Larger power systems helped lower costs, which stimulated demand for electricity, especially in homes.
http://ieee-virtual-museum.org/collection/tech.php?taid=&id=2345846&lid=1
transformer- A transformer is a device used to change the voltage of electric power. Power plants generate power at a low voltage, but power needs to be at a very high voltage for the long trips down the wires from the generator to your house. But at your house the voltage of the power has to drop back down again so that it won’t be dangerous and so your appliances aren’t blown out. A transformer allows the power to change voltages from place to place.
In 1831 Michael Faraday discovered the principles that make transformers possible. Using an induction ring Faraday discovered that an electric current flowing through one wire could have the effect of creating or “inducing” an identical current in a nearby wire. This only happens when the voltage is changing—such as when the power is snapped on and the voltage rises from 0 to its peak. The reason for the induction of a current in a nearby wire is that every flow of current in a wire results in the creation of a magnetic field around the wire. A second wire placed nearby, within that field, is influenced by the magnetism. As the field expands or collapses, it acts on the electrons in the second wire and creates a new flow of current. Winding the wire into coils makes the device more compact, and wrapping the coils onto an iron bar or ring concentrates the magnetic field in a small area. We use the name transformer because it is used in alternating current systems to raise or lower voltages. Alternating current creates a fluctuating magnetic field as it flows in a wire. If the number of turns in the first coil is lower than in the second, then higher voltage will be induced in the second coil. If the first coil has many turns, then the “secondary” voltage will be lower. Electric power systems use this principle to raise the voltage produced by a generator or dynamo to a high level, such as 100,000 volts or higher. At this high voltage, electricity can travel hundreds of miles along transmission wires without being significantly diminished. Near your home, another transformer does just the opposite—it lowers the voltage back down to 120 volts in the United States (220 volts in Europe) so that you can use it.
http://ieee-virtual-museum.org/collection/tech.php?taid=&id=2345816&lid=1
electric motor (AC & DC)-
A simple motor has six parts, as shown in the diagram below:
- Armature or rotor
- Commutator
- Brushes
- Axle
- Field magnet
- DC power supply of some sort
arc light- Electric light that uses the illumination of an electric arc maintained between two electrodes. The English chemist Humphry Davy demonstrated the electric arc in 1802 and electric arc lighting was first introduced by English electrical engineer W E Staite in 1846. The lamp consists of two carbon electrodes, between which a very high voltage is maintained. Electric current arcs (jumps) between the two electrodes, creating a brilliant light. Its main use in recent years has been in cinema projectors.
http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0016408.html
incandescent bulb-Incandescent light bulbs, such as those we commonly use in our homes, involve heating a very fine filament of wire - usually tungsten - to a high temperature, at which point the wire gives off a very bright light. The material used should have a significant intrinsic electrical resistance. Simple application of a high voltage to a very thin wire then causes intense heating in the wire and a very bright light results. The wire must be enclosed in a sealed, inert environment. All air is removed from the bulb and an inert gas such as argon is introduced to prevent the tungsten simply reacting with oxygen and catching fire. The tungsten is thus unaffected by the process which can be continued indefinitely. The main cause of failure of tungsten filament lamps is the speed of heating and cooling when the lamp is switched on and off. This results in thermal fatigue - the wire breaks because of repeated expansion and contraction and the bulb fails.
http://www.btinternet.com/~k.trethewey/incandescant_light_bulb.htm
diode-A diode is a semiconductor device which allows current to flow through it in only one direction. Although a transistor is also a semiconductor device, it does not operate the way a diode does. A diode is specifically made to allow current to flow through it in only one direction.
http://www.interq.or.jp/japan/se-inoue/e_diode.htm
transistor-The transistor is a three terminal, solid state electronic device. In a three terminal device we can control electric current or voltage between two of the terminals by applying an electric current or voltage to the third terminal. This three terminal character of the transistor is what allows us to make an amplifier for electrical signals, like the one in our radio. With the three-terminal transistor we can also make an electric switch, which can be controlled by another electrical switch. By cascading these switches (switches that control switches that control switches, etc.) we can build up very complicated logic circuits. These logic circuits can be built very compact on a silicon chip with 1,000,000 transistors per square centimeter. We can turn them on and off very rapidly by switching every 0.000000001 seconds. Such logic chips are at the heart of your personal computer and many other gadgets you use today.
http://nobelprize.org/educational_games/physics/transistor/history/
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