Keisha Brent Essays (622 words) - Education, Educational Psychology

Keisha Brent October 20, 2016 Psych 3820 A New School System In order for the philanthropist plan to donate money in the development of a school system in less industrialized country and it be successful he/she would have to come up with an outline. Within the outline they would have to know exactly what they will be donating money to and would the school system run properly. For instance they would need educators, updated technology, meal plans, books other supplies in order to bring the school system into the 21 st century. T his plan may or may not work due to the fact that the country more than likely have other economic problems and putting money towards education may backfire if things don't go right. Also the country more than likely have their own traditional way of living and became equipped with their daily routines. While the term "21st-century " is generally used to refer to certain core competencies such as collaboration, digital literacy, critical thinking, a nd problem-solving that help people strive to be successful and keep up with today's society. Being that this is a poor, rural, agricultural less industrialized country it would more than likely take time for everyone to adapt. Another thing the philanthropist may need to know is that there are differe nt types of learning; formal, non-formal, and informal . A formal example would be school and t o become truly literate in a 21st century classroom, it would seem both teache rs and students not only need a capable, working knowledge of the technologies available to them, but also knowledge about how to utilize those devices in such a way that meaningful learning occurs inside and outside of the classroom. Then th ere's non-formal , which would be educational programming aimed at those left out of formal education. This would be the discards of school system who usually are non-literate, making it more challenging for them to catch on to such an updated system. Lastly the informal way of learn ing normally would be taught by parents, peers, community members, etc which would also be the less likely to be affected by the "21 st century", upbringing. I say this becaus e people tend to learn things faster when they're raised around advanced technology and system updates, they become more immune. I n America we have come to value formal educa tion/ learning as a step ping stone to better opportunities career and skill wise, set apart from our context of daily living. In addit ion formal learning in the 21 st century here, teachers are responsible for imparting knowledge and skill, along with; learning via verbal exchange and teaching by verbal presentation. Were as we view informal here in America as embedded in our daily life activities and the learner is responsible for obtaining knowledge and skills. Usually learning by observation and imitation, while teaching via demonstration. Both being two good ways of learning and normally goes hand in hand. Over all the philanthropist plan would impact the traditional culture of the country significantly depending on how far behind there culture is from our 21 st century culture in America. Being that our technologies for most classrooms include such things as desktop and laptop computers, LCD pro jectors and SMART boards, w ith so many different technologies available, educators have their hands full trying to keep up with all the workings o f these capabilities. But once everyone get the hang of things the transition may be smooth and the plan could succeed with the right people and proper training. If the philanthropist really invest a wealthy amount of money its possible but will take time.

The Presidency of FDR essays

The Presidency of FDR essays In 1932, Americans realized that they had an increasingly great financial problem on their hands, and tried to correct it by centralizing power. The President contained so much power that the nation almost became communism, especially with Roosevelt's introduction of the New Deal. When Franklin Roosevelt became President of the United States in 1933, the nation was in the depths of the worst depression it had ever experienced. President Roosevelt, a very energetic and enthusiastic person, inspired the people with his own confidence and faith in the future. He gathered a group of people sharing his views to help him, and provided food, clothing, and shelter for millions of unemployed Americans. This was part of what he called the New Deal, of which his three objectives were relief, recovery, and reform for American citizens. In another attempt at recovery, Congress attempted to revive the nation's agriculture and industry and place the economy in good position. They printed extra money to lend to industries that quickly paid it back. By 1933 nearly 14 million Americans were out of work. In response, the Roosevelt administration immediately launched what seemed at the time to be a wonderful program of direct relief. In two years, federal agencies distribute d three billion dollars to the states. However, the people unemployed wanted jobs, not welfare, thus the Works Progress Administration came into existence. This helped restore some of the lost jobs. By 1936, the New Deal program faced a large body of opposition, from within the Democratic Party itself. Many critics felt that the government was interfering too much with the free enterprise system, and was threatening individualism and democracy. This excess of power by Roosevelt is what is known as the Imperial Presidency. By the end of 1938, the opposition had become so strong that President Roosevelt decided to hold back other large reforms he ...

Cyrus McCormick, Inventor of the Mechanical Reaper

Cyrus McCormick, Inventor of the Mechanical Reaper Cyrus McCormick (February 15, 1809–May 13,  1884), a Virginia blacksmith, invented the mechanical reaper  in 1831. Essentially a horse-drawn machine that harvested wheat, it was one of the most important inventions in the history of farm innovation. The reaper, which one observer  likened to a cross between a wheelbarrow and a chariot, was capable of  cutting six acres of oats in one afternoon, the equivalent of 12 men working with scythes. Fast Facts: Cyrus McCormick Known For: Invented the mechanical reaperKnown As: The Father of Modern AgricultureBorn: February 15, 1809 in Rockbridge County,  VirginiaParents: Robert McCormick, Mary Ann HallDied: May 13, 1884 in Chicago, IllinoisSpouse: Nancy Nettie FowlerChildren: Cyrus McCormick Jr., Harold Fowler McCormickNotable Quote: Indomitable perseverance in a business, properly understood, always ensures ultimate success. Early Life McCormick was born in 1809 in Rockbridge County, Virginia, to Robert McCormick and Mary Ann Hall McCormick, who had migrated from Great Britain. He was the eldest of eight children in a family that was influential in the area. His father was a farmer but also a blacksmith and an inventor. Young McCormick had little formal education, spending his time instead in his fathers workshop. His father held patents for inventing such farm machinery as a clover huller, a blacksmith’s bellows, a hydraulic power machine, and other labor-saving devices for the farm, but after more than 20 years he had failed to come up with a workable, horse-drawn mechanical reaping machine. Cyrus decided to take up the challenge. Seeds of the Reaper McCormicks invention would make him prosperous and famous, but he was a religious young man who believed his mission was to help feed the world. For farmers in the early 19th century, harvesting required a large number of laborers. He set out to reduce the number of hands needed for the harvest. He  drew on the work of many other people in developing the reaper, including that of his father and Jo Anderson, one of his fathers slaves, but he ended up basing his work on principles entirely different from those employed by Robert McCormick. After 18 months, he came up with a working model. His machine had a vibrating cutting blade, a reel to pull the grain within reach of the blade, and a platform to catch the falling grain. He had succeeded, and he was only 22. The first version was rough- it made such a clatter that slaves were assigned to walk with the frightened horses to keep them calm- but it clearly worked. He received a patent for his invention in 1834. Ironically, after he had received the patent, McCormick set aside his invention to focus on his familys iron foundry, which failed in the wake of the bank panic of 1837 and left the family deeply in debt. So he returned to his reaper, setting up production in a shop next to his fathers house and focusing on improvements. He finally sold his first machine in 1840 or 1841, and business slowly took off. Moves to Chicago A visit to the Midwest convinced McCormick that the future of his reaper was in that sprawling, fertile land instead of the rocky soil in the East.  Following more improvements, he and his brother Leander opened a factory in Chicago in 1847 and sold 800 machines that first year. The new venture, the McCormick Harvesting Machine Co., eventually became the largest farm equipment manufacturing firm in the country. In 1851, McCormick gained international fame when his reaper won the Gold Medal at the landmark Great Exposition in Londons Crystal Palace. He became a leading public figure and remained active in Presbyterian causes as well as Democratic politics. In 1871, the  Great Chicago Fire  destroyed McCormicks company, but the family rebuilt it and McCormick continued to innovate. In 1872, he produced a reaper that  automatically bound the bundles with wire. Eight years later, he came out with a binder that, using a knotting device invented by Wisconsin pastor John F. Appleby, bound the handles with twine.  Despite fierce competition and legal battles over patents, the company continued to prosper. Death and Tragedy McCormick died in 1884, and his eldest son, Cyrus Jr., took over as president at only 25 years old. Two years later, though, the business was marked by tragedy. A workers strike in 1886 that involved the McCormick Harvesting Machine Co. eventually turned into one of the worst labor-related riots in American history. By the time the Haymarket Riot ended, seven policemen and four civilians were dead. Charges were brought against eight reputed anarchists: Seven were sentenced to death; one committed suicide in prison, four were hanged, and the sentences of two were commuted to life in prison. Cyrus McCormick Jr. continued as president of the company until 1902, when J.P. Morgan bought it, along with five others, to form the International Harvester Co. Legacy Cyrus McCormick is remembered as â€Å"The Father of Modern Agriculture because he  made it possible for farmers to expand their small, personal farms into much larger operations. His reaping machine brought an end to hours of tedious fieldwork and encouraged the invention and manufacture of other labor-saving  farm implements and machinery. McCormick and his competitors continued to improve their products, leading to such innovations as self-raking reapers, with a continually moving canvas belt that delivered the cut grain to two men riding on the end of the platform, who bundled it.   The reaper was eventually replaced by the self-propelled combine, operated by one man, which cuts, gathers, threshes, and sacks the grain mechanically. But the original reaper was the first step in a transition from hand labor to the mechanized farming of today. It brought about an industrial revolution, as well as a vast change in agriculture. Sources Cyrus McCormick. InventionWare.com.McCormick, Cyrus Hall. American National Biography.Cyrus McCormick: American Industrialist and Inventor. Encylopedia Brittanica.Nancy Fowler McCormick. Revolvy.Cyrus McCormick Biography. TheFamousPeople.com.

Bronfenbrenner Analysis Research Paper Example | Topics and Well Written Essays - 1500 words

Bronfenbrenner Analysis - Research Paper Example The theory largely illustrates how the environmental factors affect early education of a child towards full maturity. Though many theories put more emphasis on the nurture vs. nature relation (Paquette and Ryan, 2), Bronfenbreenner’s ecological system theory goes deeper into the perspective of the child’s environment in terms of the quality and context of the child’s environment. Therefore, in order to understand human development in a better perspective of the entire ecological system has to be considered and its relation to the growth and development of the child. This involves considering the micro systems that refer to the relationship between the developing person, the environment and the macros system, which refers to institutional patterns that include customs, economy and bodies of knowledge. The theory is much detailed and goes beyond the facts considered by other developmental theories in child development. Bronfebrenner (38) explains that the first proposition of the general ecological model state that especially in the early stages and largely to the entire life, the human development takes process though complex, reciprocal and progressive process that interacts between an active evolving bio-psychological human organism and the persons, objects, symbols that are in the immediate environment. The forms of interaction in the immediate environment are referred to as proximal process and may include, mother –child and child-child relationship. The theory implicates that a child has to be considered in the context of a wider scope to the social spheres of influence. The child cannot develop outside a unique historical, ideological and sociopolicatical set of circumstances. The advantage of this theory is that while others concentrate on the impacts of thinking, perception, motivation and learning that is perceived at an isolated level of

Developing Professional Practice and Using Information in HR Research Paper

Developing Professional Practice and Using Information in HR - Research Paper Example As the paper outlines, in-house and on-the-job learning approaches are the two most effectual development approaches as compared to that of the external development such as educational background, workshops and various other practices which include visual and audio practices that have not made such impact. The previous survey carried out in 2011 regarding e-learning reports that the use of the approach is increasing in a few specific departments of training and development (CIPD, 2012)  A survey done among the employees regarding the effective learning and development approach in the organization provides a report that coaching and mentoring as well as performance management is the most preferred approaches to organizational change.  The organizations are making decisions more cautiously towards developing elements such as learning and development, organizational development and performance management to ensure organizational success. The utilization of the e-learning approach am ong the employees of public sectors was more than that of the other learning and development approaches management approach attracts the highly productive employees the most in the private sector. The public sector does not include the middle managers to put them in this approach. The objectives of the talent management are to develop an efficient workforce and to develop as well as educate them to be the future managers and leaders in the organizations. Talent management is considered effective by very few organizations.  Around 50% of organizations consider talent management as reasonably effective.

HVDC Light Technology Essay Example for Free

HVDC Light Technology Essay AbstractThis document reveals theHVDC Light DC transmission technology.It is used in underground transmission and moreover provides point to point transmission.HVDC Light requires only two elements namely a converter station and a pair of ground cables. The new HVDC Light cable is an extruded, single-pole cable. It is ideally suited for feeding power into growing metropolitan areas from a suburban substation. HVDC Light is inherent environmentally friendly cables instead of OH transmission lines. Virtually no magnetic field. The environmental gains would be substantial, since the power supplied via the DC cables will be transmitted from efficient power plants in the main AC grid. 1. INTRODUCTION A hundred years ago, the transformer and a new transmission and distributionbe controlled precisely and independentlycan replace overhead lines at no costcontrol capabilities that are not present oreconomically feasible to connect smallscale,Equally important, HVDC Light hasfor inefficient, polluting local generationfrequency, active and reactive power canislands, mining districts and drillingloads from a main AC-gridof each other. This technology also relieson a new type of underground cable which penalty platforms can be supplied with power frompossible even in the most sophisticated ACrenewable power generation. Renewable power generation plantssuch as diesel units. The voltage, . Connect small scale Feeding remote isolated Flexible transmission System technology, HVDC Light, makes it the main grid,thereby eliminating the needto the main AC grid. Vice versa,using thevery same technology, remote locations asthe three phase system made it possible totransmit AC power efficiently and economically over vast distances and todistributethe power toamultitude ofusers.Since then all aspects of transmission anddistribution have developed by means oftechnical improvement and evolution. This AC transmission and distributiontechnology has made it possible to locategeneratingplants in optimum locations, andtoutilize them efficiently. This has alsoresulted in great environmental gains.Thermal plants have been located wherethey can be supplied with fuel through anefficient transportation system, therebyreducing waste and pollution. Hydro plantshave been located where the hydroresources can be used at the greatestadvantage. And large generating plantshave meant fewer overhead lines than amultitude of smaller generating plantswould have required.However, today’s AC transmission anddistribution systems are, at least inprinciple, based on ideas that haven’tchanged much since a hundred years ago. To transmit power, step up the voltage withtransformers, transmit power, step downthe voltage and distribute power. Despitetheir proven advantages, it is difficult andexpensive to adapt AC transmission anddistribution systems to the numerous smallscalegenerating plants that are being built,or to the increasingly complex and variableproduction and load demands.Environmental concerns and regulationsalso put heavy restrictions on building right-of-ways and on small-scale, fossilfuelledgenerating plants, such as dieselgenerating plants.These new trends require networks that areflexible. The networks must be able to copewith large variations in load and frequentchanges in productions patterns with tougher environmental regulations.Also, in such flexible networks, the powerflow and the voltages require precisecontrol in order to make the grids stable and economic. 2. TECHNOLOGY As its name implies, HVDC Light is a DCtransmission technology. However, it isdifferent from the classic HVDCtechnology used in a large number oftransmission schemes. Classic HVDCtechnology is mostly used for large point-to-point transmissions, often over vastdistances across land or under water. It requires fast communications channelsbetween the two stations, and there mustbe large rotating units generators orsynchronous condensers present in theAC networks at both ends of thetransmission. HVDC Light consists of only two elements: a converter station and a pair ofground cables. The converters are voltagesource converters, VSC’s. The output from the VSCare determined by the controlsystem, which does not require anycommunications links between the differentconverter stations. Also, they don’t need torely on the AC network’s ability to keepthe voltage and frequency stable. Thesefeatures make it possible to connect theconverters to the points bests suited for theAC system as a whole. Power range up to 100 MW Independent control of active and reactive power Can feed power to AC network without ownGeneration DC The converter station is designed for apower range of 1-100 MW and for a DCvoltage in the 10-100 kV range. One suchstation occupies an area of less than 250sq. m. (2 700 sq. ft.), and consists ofjust a few elements: two containers for theconverters and the control system, threesmall AC air-core reactors, a simpleharmonics filter and some cooling fans. 20MW:18x12m The converters are using a set of six valves,two for each phase, equipped with highpowertransistors, IGBT (Insulated GateBipolar Transistor). The valves arecontrolled by a computerized controlsystem by pulse width modulation, PWM.Since the IGBTs can be switched on or off, the output voltages and currents onthe AC side can be controlled precisely.The control system automatically adjuststhe voltage, frequency and flow of activeand reactive power according to the needsof the AC system.The PWM technology has been tried andtested for two decades in switched powersupplies for electronic equipment ascomputers. Due to the new, high powerIGBTs, the PWM technology can now beused for high power applications as electricpower transmission.HVDC Light can be used with regularoverhead transmission lines, but it reachesits full potential when used with a new kindof DC cable. The new HVDC Light cable isan extruded, single-pole cable. As anexample a pair of cables with a conductorof 95 sq mm aluminum can carry a load of30 MW at a DC voltage of +/-100KV.Handling the cable is easy. Despite its large power-carrying capacityit has a specific weight of just over 1 kg/m.Contrary to the case with AC transmission;distance is not the factor that determinesthe line voltage. The only limit is the costof the line losses, which may be lowered bychoosing a cable with a conductor with alarger cross section. Thus, the cost of apair of DC cables is linear with distance. Insulation: 5.5 mm triple extruded Screen: Copper wire Sheath: HDPE Weight: 1.05 kg/m Voltage: 100 kV DC Current: 300 A Power: 30 MW Conductor: 95 mm^2Aluminum A DC cable connection could be more costefficientthan even a medium distance ACoverhead line, or local generating unitssuch as diesel generators.The converter stations can be used indifferent grid configurations. A singlestation can connect a DC load or generatingunit, such as a photo-voltaic power plant,with an AC grid. Two converter stationsand a pair of cables make a point-to pointDC transmission with AC connections ateach end. Three or more converter stationsmake up a DC grid that can be connected toone or more points in the AC grid or todifferent AC grids. An HVDCLight network can be configured radial or meshed,like any network. The DC grids can be radial with multi-dropconverters, meshed or a combination ofboth. In other words, they can beconfigured, changed and expanded in muchthe same way AC grids are. 3. APPLICATIONS 3.1 OVERHEAD LINES In general, it is getting increasingly difficultto build overhead lines. Overhead lineschange the landscape, and the constructionof new lines is often met by public resentment and political resistance. Peopleare often concerned about the possiblehealth hazards of living close to overheadlines. In addition, a right-of-way for a high voltage line occupant valuable land. Theprocess of obtaining permissions forbuilding new overhead lines is alsobecoming time-consuming and expensive.Laying an underground cable is a mucheasier process than building an overheadline. A cable doesn’t change the landscapeand it doesn’t need a wide right-of-way.Cables are rarely met with any publicopposition, and the electromagnetic fieldfrom a DC cable pair is very low, and also astatic field. Usually, the process ofobtaining the rights for laying anunderground cable is much easier, quickerand cheaper than for an overhead line.A pair of HVDC Light cables can beplowed into the ground. Despite their largepower capacity, they can be put in placewith the same equipment as ordinary, AChigh voltage distribution cables. Thus,HVDC Light is ideally suited for feedingpower into growing metropolitan areasfrom a suburban substation. 3.2 REPLACING LOCAL GENERATION Remote locations often need localgeneration if they are situated far awayfrom an AC grid. The distance to the gridmakes it technically or economicallyunfeasible to connect the area to the maingrid. Such remote locations may be islands,mining areas, gas and oil fields or drillingplatforms. Sometimes the local generators use gas turbines, but diesel generators aremuch more common.An HVDC Light cable connection could bea better choice than building a local powerplant based on fossil fuels. Theenvironmental gains would be substantial,since the power supplied via the DC cableswill be transmitted from efficient powerplants in the main AC grid. Also, thepollution and noise produced when thediesel fuel is transported will be completelyeliminated by an HVDC line, as the needfor frequent maintenance of the diesels.Since the cost of building an HVDC Lightline is a linear function of the distance, abreak-even might be reached for as shortdistances as 50- 60 km. HVDC Light lowest cost AC + Overhead line HVDC Light + cable Cost inside AC grid Distance from the AC grid eliminate local diesel Cost/kWh 3.3 CONNECTING POWER GRIDS Renewable power sources are often builtfrom scratch, beginning on a small scaleand gradually expanded. Wind turbine farms is the typical case, but this is alsotrue for photovoltaic power generation.These power sources are usually locatedwhere the conditions are particularlyfavorable, often far away from the mainAC network. At the beginning, such aslowly expanding energy resource cannotsupply a remote community with enoughpower. An HVDC Light link could be anideal solution in such cases.First, the link could supply the communitywith power from the main AC grid,eliminating the need for local generation.The HVDC Light link could also supply thewind turbine farm with reactive power for the generators, and keeping the powerfrequency stable.When the power output from the windgenerators grows as more units are added,they may supply the community with asubstantial share of its power needs. Whenthe output exceeds the needs of theCommunity, the power flow on the HVDCLight link is reversed automatically, and thesurplus power is transmitted to the mainAC grid. Wind power Small scale hydropower HVDC Light Extruded cable Distant ac- grid Waste gas is usually burned at offshoredrillingplatforms, since it is too expensive,or technically difficult, to use the gas for power generation and transmit it by an ACcable to the main grid on the shore. Thus,the energy content of the gas is wasted, andthe primitive burning process is source ofpollution. With an HVDC Lightunderwater cable transmission, the gas canbe used as gas turbine fuel, supplying boththe platform and the main AC grid withpower. The process of burning the gas ingas turbines would also produce much acleaner exhaust than simple burning woulddo.The DC underwater cable network could easily be extended to other offshoreplatforms. 3.4 ASYNCRONOUS LINKS Two AC grids, adjacent to each other butrunning asynchronously with respect toeach other, cannot exchange any powerbetween each other. If there is a surplus ofgenerating capacity in one of the grids itcannot be utilized in the other grid. Each ofthe networks must have its own capacity of peak power generation, usually in the formof older, inefficient fuel fossil plants, ordiesel or gas turbine units. Thus, peakpower generation is often a source ofsubstantial pollution, and their fueleconomy is frequently bad.A DC link, connecting two such networks,can be used for combining the generationcapacities of both networks. Cheap surpluspower from one network can replace peakpower generation in the other. This willresult in both reduced pollution levels andincreased fuel economy. The powerexchange between the networks is alsovery easy to measure accurately. 4. ADVANTAGES * Transmission by HVDC Light saves the environment by replacing local fossil-fueled generation withtransmission from main AC-grid. * Connecting small scale renewable power to main AC –grid. * HVDC Light is inherent environmentally friendlycables instead of OH transmission lines. * Virtually no magnetic field. * No ground currents because of bipolar transmission. 5. CONCLUSION HVDC Light technology saves theenvironment by replacing remote fossilfuelledgenerators with cost-efficienttransmission of power from efficient andclean, large-scale generation productionunits. The efficiency of a modern, largescale, thermal generating plant is usually 25percent higher than that for a modernsmall or moderate scale diesel generatorplant,Vice versa, HVDC Light provides aconvenient and cost-effective way forconnecting renewable and non-pollutingenergy sources as wind power farms andphotovoltaic power plants to a main grid.The HVDC Light technology in itself hasstrong environmental benefits. Since poweris transmitted via a pair of underground cables, the electromagnetic fields from thecables cancel each other. Any residual fieldis a static field, as opposed to the powerfrequencyfields radiated from AC cables.Since HVDC Light transmissions arebipolar, they do not inject any currents intothe ground. Ground currents can disturbcommunications systems or causecorrosion on gas or oil pipelines.A pair of light-weight DC cables can beeasily plodded into the ground at a costthat is comparable to or less than for acorresponding AC overhead line. Asopposed to an overhead line, anunderground cable pair has no visualimpact at all on the landscape. Usually it’salso much easier to obtain permissions andpublic approval for a cable transmissionthan for an overhead line, especially inresidential areas. ACKNOWLEDGEMENT Our sincere thanks to HOD and FACULTIES for encouraging us to prepare the above document. A special thanks to IEEE.org REFERNCES [1] K. Eriksson, â€Å"HVDC Lightâ„ ¢ and development of Voltage SourceConverters†, IEEE TD 2002 Latin America, Sà £o Paulo, Brazil, March. [2] L. Carlsson, G. Asplund, H. Bjà ¶rklund, M. Ã…berg, Present trends inHVDC converter station design IV SEPOPE Conference, Foz doIguacu, Brazil. [3]IEEE explorer.org

Semiconductors: The Silicon Chip Essay examples -- science

Semiconductors: The Silicon Chip Silicon is the raw material most often used in integrated circuit (IC) fabrication. It is the second most abundant substance on the earth. It is extracted from rocks and common beach sand and put through an exhaustive purification process. In this form, silicon is the purist industrial substance that man produces, with impurities comprising less than one part in a billion. That is the equivalent of one tennis ball in a string of golf balls stretching from the earth to the moon. Semiconductors are usually materials which have energy-band gaps smaller than 2eV. An important property of semiconductors is the ability to change their resistivity over several orders of magnitude by doping. Semiconductors have electrical resistivities between 10-5 and 107 ohms. Semiconductors can be crystalline or amorphous. Elemental semiconductors are simple-element semiconductor materials such as silicon or germanium. Silicon is the most common semiconductor material used today. It is used for diodes, transistors, integrated circuits, memories, infrared detection and lenses, light-emitting diodes (LED), photosensors, strain gages, solar cells, charge transfer devices, radiation detectors and a variety of other devices. Silicon belongs to the group IV in the periodic table. It is a grey brittle material with a diamond cubic structure. Silicon is conventionally doped with Phosphorus, Arsenic and Antimony and Boron, Aluminum, and Gallium acceptors. The energy gap of silicon is 1.1 eV. This value permits the operation of silicon semiconductors devices at higher temperatures than germanium. Now I will give you some brief history of the evolution of electronics which will help you understand more about semiconductors and the silicon chip. In the early 1900’s before integrated circuits and silicon chips were invented, computers and radios were made with vacuum tubes. The vacuum tube was invented in 1906 by Dr.Lee DeForest. Throughout the first half of the 20th century, vacuum tubes were used to conduct, modulate and amplify electrical signals. They made possible a variety of new products including the radio and the computer. However vacuum tubes had some inherent problems. They were bulky, delicate and expensive, consumed a great deal of power, took time to warm up, got very hot, and eventually burned out. The first digital computer c... ..., the second mask pattern is exposed to the wafer, and the oxide is etched away to reveal new diffusion areas. The process is repeated for every mask - as many as 18 - needed to create a particular IC. Of critical importance here is the precise alignment of each mask over the wafer surface. It is out of alignment more than a fraction of a micrometer (one-millionth of a meter), the entire wafer is useless. During the last diffusion a layer of oxide is again grown over the water. Most of this oxide layer is left on the wafer to serve as an electrical insulator, and only small openings are etched through the oxide to expose circuit contact areas. To interconnect these areas, a thin layer of metal (usually aluminum) is deposited over the entire surface. The metal dips down into the circuit contact areas, touching the silicon. Most of the surface metal is then etched away, leaving an interconnection pattern between the circuit elements. The final layer is "vapox", or vapour-deposited- oxide, a glass-like material that protects the IC from contamination and damage. It, too, is etched away, but only above the "bonding pads", the square aluminum areas to which wires will later be attached. Semiconductors: The Silicon Chip Essay examples -- science Semiconductors: The Silicon Chip Silicon is the raw material most often used in integrated circuit (IC) fabrication. It is the second most abundant substance on the earth. It is extracted from rocks and common beach sand and put through an exhaustive purification process. In this form, silicon is the purist industrial substance that man produces, with impurities comprising less than one part in a billion. That is the equivalent of one tennis ball in a string of golf balls stretching from the earth to the moon. Semiconductors are usually materials which have energy-band gaps smaller than 2eV. An important property of semiconductors is the ability to change their resistivity over several orders of magnitude by doping. Semiconductors have electrical resistivities between 10-5 and 107 ohms. Semiconductors can be crystalline or amorphous. Elemental semiconductors are simple-element semiconductor materials such as silicon or germanium. Silicon is the most common semiconductor material used today. It is used for diodes, transistors, integrated circuits, memories, infrared detection and lenses, light-emitting diodes (LED), photosensors, strain gages, solar cells, charge transfer devices, radiation detectors and a variety of other devices. Silicon belongs to the group IV in the periodic table. It is a grey brittle material with a diamond cubic structure. Silicon is conventionally doped with Phosphorus, Arsenic and Antimony and Boron, Aluminum, and Gallium acceptors. The energy gap of silicon is 1.1 eV. This value permits the operation of silicon semiconductors devices at higher temperatures than germanium. Now I will give you some brief history of the evolution of electronics which will help you understand more about semiconductors and the silicon chip. In the early 1900’s before integrated circuits and silicon chips were invented, computers and radios were made with vacuum tubes. The vacuum tube was invented in 1906 by Dr.Lee DeForest. Throughout the first half of the 20th century, vacuum tubes were used to conduct, modulate and amplify electrical signals. They made possible a variety of new products including the radio and the computer. However vacuum tubes had some inherent problems. They were bulky, delicate and expensive, consumed a great deal of power, took time to warm up, got very hot, and eventually burned out. The first digital computer c... ..., the second mask pattern is exposed to the wafer, and the oxide is etched away to reveal new diffusion areas. The process is repeated for every mask - as many as 18 - needed to create a particular IC. Of critical importance here is the precise alignment of each mask over the wafer surface. It is out of alignment more than a fraction of a micrometer (one-millionth of a meter), the entire wafer is useless. During the last diffusion a layer of oxide is again grown over the water. Most of this oxide layer is left on the wafer to serve as an electrical insulator, and only small openings are etched through the oxide to expose circuit contact areas. To interconnect these areas, a thin layer of metal (usually aluminum) is deposited over the entire surface. The metal dips down into the circuit contact areas, touching the silicon. Most of the surface metal is then etched away, leaving an interconnection pattern between the circuit elements. The final layer is "vapox", or vapour-deposited- oxide, a glass-like material that protects the IC from contamination and damage. It, too, is etched away, but only above the "bonding pads", the square aluminum areas to which wires will later be attached.