Ohms law Essay Example for Free

Ohms law Essay An electronics factory needs resistors of 5 ohms and 15 ohms for a new electrical device. My task is to investigate how the resistance of a piece of wire depends on length and to find the length of the wire needed to make the required resistors, using only 4 volts. Introduction/Planning A selection of different wires made from constantan and nichrome and the usual laboratory apparatus will be available for me. Wire A Constantan wire of approximate diameter 0. 3mm Wire B Constantan wire of approximate diameter 0. 4mm Wire C Constantan wire of approximate diameter 0. 3mm A constantan is an alloy whose resistance stays fairly constant when it becomes hot. In fact the resistance changes by less than 0. 5% even when the temperature rises by a few hundred degrees. Nichrome, along with other metals, is an alloy whose temperature does change appreciably when it becomes hot. Before starting my coursework, I have to find the variables in the experiment, safety aspects etc. I found that a number of things affect the resistance of a wire. Below is a list of factors and reasons why they affect the resistance of a wire. From this list of factors I have to make sure that these factors remain constant or excluded from the experiment. We are only investigating length but the other variables may change our outcomes. In electricity, resistance is the ratio of the potential difference (p. d. or voltage) across a conductor to the electrical current, which flows through it as a result. The unit of measurement is the ohm (O), this being the resistance of a conductor requiring a potential difference of 1 volt across its ends to produce a current of 1 ampere. For a given metal conductor at constant temperature the value is the same whatever the current (Ohms law), but rises if the temperature rises. Any conductor possessing resistance gives off heat when a current flows through it. Joules law describes this effect. Resistance occurs when the electrons travelling along the wire collide with the atoms of the wire. These collisions slow down the flow of electrons causing resistance. Resistance is a measure of how hard it is to move the electrons through the wire. Ohms law: The current flowing through a metal is proportional to the potential difference across it, provided that the temperature remains constant. We are going to use metals, which obey ohms law, metals which give us a constant value for resistance (gradient). Resistance (? ) = P. d across the wire (V) / Current through the wire (A) Current flows in an electric circuit in accordance with several definite laws. The basic law of current flow is Ohms law, named for its discoverer, the German physicist Georg Ohm. Ohms law states that the amount of current flowing in a circuit made up of pure resistances is directly proportional to the electromotive force impressed on the circuit and inversely proportional to the total resistance of the circuit. The law is usually expressed by the formula I = V/R, where I is the current in amperes, V is the electromotive force in volts, and R is the resistance in ohms Ohms law applies to all electric circuits for both direct current (DC) and alternating current (AC), but additional principles must be invoked for the analysis of complex circuits and for AC circuits also involving inductances and capacitances. A series circuit as on page 5, is one in which the devices or elements of the circuit are arranged in such a way that the entire current (I) passes through each element without division or branching into parallel circuits. When two or more resistances are in series in a circuit, the total resistance may be calculated by adding the values of such resistances. If the resistances are in parallel, the total value of the resistance in the circuit is given by the formula: In a parallel circuit, electrical devices, such as incandescent lamps or the cells of a battery, are arranged to allow all positive (+) poles, electrodes, and terminals to be joined to one conductor, and all negative (-) ones to another conductor, so that each unit is, in effect, on a parallel branch. The value of two equal resistances in parallel is equal to half the value of the component resistances, and in every case the value of resistances in parallel is less than the value of the smallest of the individual resistances involved. In AC circuits, or circuits with varying currents, circuit components other than resistance must be considered. If a circuit has a number of interconnected branches, two other laws are applied in order to find the current flowing in the various branches. These laws, discovered by the German physicist Gustav Robert Kirchhoff, are known as Kirchhoffs laws of networks. The first of Kirchhoffs laws states that at any junction in a circuit through which a steady current is flowing, the sum of the currents flowing to the point is equal to the sum of the currents flowing away from that point. The second law states that, starting at any point in a network and following any closed path back to the starting point, the net sum of the electromotive forces encountered will be equal to the net sum of the products of the resistances encountered and the currents flowing through them. This second law is simply an extension of Ohms law. The application of Ohms law to circuits in which there is an alternating current is complicated by the fact that capacity and inductance are always present. Inductance makes the peak value of an alternating current lag behind the peak value of voltage; capacitance makes the peak value of voltage lag behind the peak value of the current. Capacitance and inductance inhibit the flow of alternating current and must be taken into account in calculating current flow. The current in AC circuits can be determined graphically by means of vectors or by means of the algebraic equation, in which L is inductance, C is capacitance, and f is the frequency of the current. The quantity in the denominator of the fraction is called the impedance of the circuit to alternating current and is sometimes represented by the letter Z; then Ohms law for AC circuits is expressed by the simple equation I = V/Z. We know that all instruments have an error on its measurement, so the way to work out the percentage error is: Percentage error = (error / measured value) i 100 Conduction in metals In metals, atoms contain protons, nucleus and lose electrons which orbit around the nucleus. Below, I have investigated conduction in metals and how they affect resistance. METAL LATTICE (Electrons move in a random direction. ) METAL LATTICE (Electrons with power pack in a particular direction. ) Variables Length: If the length of the wire is increased then the resistance will also increase as the electrons will have a longer distance to travel and so more collisions will occur. Due to this, the length increase should be proportional to the resistance increase. Thickness: If the wires thickness is increased the resistance will decrease. This is because of the increase in the space for the electrons to travel through. Due to this increased space between the atoms, there should be fewer collisions. The number of free electrons changes from one material to another. The size of the ions changes from one material to another, this affects the current and therefore affects the resistance. The arrangement and size of the atoms change from one material to another. So if there is a kink in the wire this will change the thickness of the wire. Temperature: If the wire is heated up the atoms in the wire will start to vibrate because of their increase in energy.

Why Were Bulgaria and Romania Accepted in the EU?

Why Were Bulgaria and Romania Accepted in the EU? Why were Bulgaria and Romania accepted in the EU in 2007 despite of their incomplete democratisation, which was acknowledged by the European Commission? Introduction On December 2007 Romania and Bulgaria joined the European Union. They had not been able to join in the 2004 EU expansion as they had failed to meet the EU’s criteria for membership at the time. In 2007 however there still existed serious doubts as to whether Romania or Bulgaria would be able to join. Although both were democracies both nations still had major political issues relating to corruption, government accountability and their incomplete democratisation process. Why then, if the EU acknowledged that both Countries still had serious problems, were these nations accepted into the EU? This Essay will look at the circumstances leading up to Bulgaria and Romania’s entry into the EU, examine why many believed they were not ready for membership and the reasons behind their acceptance by Brussels. Background to Membership In 2004 eight Eastern European Countries were admitted into the EU. Both Bulgaria and Romania were turned down for full membership of the EU at this point, due to their being significantly behind the other eight nations in terms of GDP, democratisation and other factors.[1] However both nations soon went from being candidates to being accession Countries in April 2005, as long as both nations continued to enact the necessary reforms, and in September 2006 it was confirmed that both would become full members on January 2007.[2] In many ways then the final decision regarding Romanian and Bulgarian membership was not made in January 2007, but arguably as early as 2005, which then made it inevitable. Throughout this period, there were serious doubts about the Eastern European Nations ability and willingness to enact the necessary reforms, and even upon entry the EU acknowledged that there was still much work to be done. Democratic Deficiencies The 2004 Romanian election was said by many commentators to be proof that the Country had not yet made the transition to fully fledged democracy. There were allegations of voter irregularities, missing votes and candidates with links to the previous security apparatus of the Country. [3] Both nations’ political systems still had aspects of authoritarian regimes, and a year after membership both were still unable to fully guarantee their citizens constitutional rights. Romania and Bulgaria’s legal systems were considered by many as incompatible with a free and democratic society.[4] In economic terms the two ex communist nations were extremely poor, with a GDP around just 30% of the EU average. At the time of the accession process both markets had not yet made the transition into being free market economies, infrastructure was ageing and the State still had a large role in both Nations economies. The most significant problem however was the widespread corruption in the S tates, especially with regards to Bulgaria. The EU consistently complained about Bulgarian organised crime’s links with high level Bulgarian Government officials, who have often been found siphoning EU grants meant for infrastructure to family businesses or to criminal gangs. Such is the level of corruption that the EU saw fit to withhold 486 million Euros worth of aid in 2008.[5] Reasons for Membership Taking into account the serious problems, poverty, corruption and lack of accountability of Romania and Bulgaria, why did the EU allow them membership in January 2007? As we have already mentioned, the decision to accept Romania and Bulgaria as members was taken long before 2007. Although they were rejected as full members in 2004, from their acceptance as accession Countries in 2005 it was clear that they were on the path to full membership. The EU did place stringent conditions on full membership, to which it is debatable the pair have achieved. The EU did judge in 2006 that both Countries, although having a lot of work to do, had satisfied the criteria. Both Romania and Bulgaria had, since 2004 reformed their legislative systems, economies and political processes.[6] From this point on, although the EU could delay membership, it could not feasibly deny membership to the two unless there was some major breach of democratic and human rights norms. Membership as a means to Reform Along with the legal arguments, Brussels clearly believed that to deny membership when the nations had clearly made profound transitional steps to reform would not only be unfair but damaging to the EU, Romania and Bulgaria. The EU believed that membership would act as a motivating factor for both nations to continue reforms, whereas rejection might well have convinced the elites of both nations to continue their corrupt and undemocratic practices. The obvious financial and political benefits that come with membership, have, as predicted by the EU, helped both nations start the economic reforms needed.[7] This essay believes that the reason Romania and Bulgaria were accepted was because the EU believed that only membership would help the Countries to successfully integrate into Europe, and that despite several problems regarding corruption and accountability, the EU was satisfied with both the existing reforms and pledges that the two nations would in future continue to meet EU expec tations and demands if they were allowed membership in 2007. Bibliography Bagehot, â€Å"Europe: Balkan Blushes; Bulgaria, Romania and the EU† (The Economist, London July 26, 2008, Vol 388, Issue 8590 Ciobanu, Monica â€Å"Romania’s travails with democracy and accession to the European Union† Europe-Asia Studies, 59.8, pp1429-1450 Pridham, Geoffrey â€Å"The Scope and Limitations of Political Conditionality: Romania’s Accession to the European Union† (Comparative European Politics, Houndsmills, Dec 2007, Vol 5, Issue 4, pp347-367) Sangiovanni, Mette Eilstrup â€Å"Debates on European Integration† (Palgrave Macmillan, New York, 2006) Website BBC News – â€Å"EU approves Bulgaria and Romania† – 26/09/2006 – accessed 10/12/2008 http://news.bbc.co.uk/1/hi/world/europe/5380024.stm 1 Footnotes [1] Sangiovanni, Mette Eilstrup â€Å"Debates on European Integration† (Palgrave Macmillan, New York, 2006, p.125) [2] Pridham, Geoffrey â€Å"The Scope and Limitations of Political Conditionality: Romania’s Accession to the European Union† (Comparative European Politics, Houndsmills, Dec 2007, Vol 5, Issue 4, pp347-367) [3] Ciobanu, Monica â€Å"Romania’s travails with democracy and accession to the European Union† Europe-Asia Studies, 59.8, p1444 [4] Pridham, Geoffrey â€Å"The Scope and Limitations of Political Conditionality: Romania’s Accession to the European Union† (Comparative European Politics, Houndsmills, Dec 2007, Vol 5, Issue 4, pp347-367) [5] Bagehot, â€Å"Europe: Balkan Blushes; Bulgaria, Romania and the EU† (The Economist, London July 26, 2008, Vol 388, Issue 8590 [6] Ciobanu, Monica â€Å"Romania’s travails with democracy and accession to the European Union† Europe-Asia Studies, 59.8, pp1429-1450 [7] Bagehot, â€Å"Europe: Balkan Blushes; Bulgaria, Romania and the EU† (The Economist, London July 26, 2008, Vol 388, Issue 8590

My Teaching Philosophy :: Essays Papers

My Teaching Philosophy Why do you want to be a teacher?This is a question I am frequently asked by rich relatives considering my choice from a monetary perspective; by my grandparents who both taught in the Bronx for 30 years; and most frequently by myself.Why do I want to teach?Why have I decided on history and social studies? In all honesty there have been many different answers to that question and the answer has changed three times since the start of this paragraph.I suppose part of being young is inconsistency.I am no different.But understanding these differences and understanding people is the key.I think I have a gift to see inside people and to help them see inside themselves.Right now there are three main reasons why I have chosen teaching history to by my life long profession, or at least until I have a mid-life crisis.These reasons are as follows: passion, ability and, no matter how clichà ©, the desire to make a difference. Since I was a child I have always been fascinated with history.I could watch the History and Discovery channels for hours. I had read the complete works of Jane Austin by the end of middle school.I used to go to the local museum and wander around for hours.In the second grade we took a field trip to see the Bill of Rights, which was on tour for its 200th birthday.Honestly, I remember very little of the actual document itself, but I will never forget the feeling.I knew it was important, because my teacher told so, and I know the awe it inspired in people.I think that is where this passion began.I received the Civil War documentary by Ken Burns on my tenth birthday and went to the Tower of London on my thirteenth.What started as awe has become my passion. What will this passion mean to my students you may ask?My father is a Roman Catholic from the Netherlands.My mother is a Jewish girl from Brooklyn.They met in a sheep field in Israel.I am a child of divorce and have a crease in my nose.The point is that I have a story.This story is more important than I can say.To know my story is know where I come from.This story, the story of my students, history is my passion.We are living it and breathing it.We are history.In my classroom I want to teach my students to care about who they are and where they come from.

What Kind of God is He? :: Religion, Genesis, Trials

God puts trials upon everyone, and in Genesis twenty-two he sets Abraham out on his own journey, to sacrifice his own son, Isaac. After all the struggle Abraham and Sarah had to conceive the child, God decides that the boy should be sacrificed to him. And without an even a moment of procrastination or a murmur of woe (Gen 22:3) the man sets off to do God’s bidding. What sort of God would ask a loyal man such as Abraham to do this appalling deed? I believe firmly, that God did not do this so that Abraham would be deprived of the wonders of his offspring, or to have a human burnt offering for his own good, but to gain our trust and show how trustworthy he is. And also to show that if we just listen to what he has to say that we too, will have everything â€Å"provided† for us when urgent times come. He trusted in Adam and Eve, whose adversity started when they turned their ears away from Him and ate the forbidden fruit (Gen 3:6). Or in the story of Cain and Abel, Cain chooses not to listen to God and committed homicide against his brother Abel (Gen 4:8) and is then sent out to Nod. Yet again, another misfortune happened when Lot’s wife ignored the commands of the Lord and looked back at the destruction of Sodom and Gomorrah, only to be turned into a pillar of salt (Gen 19:26). All these stories show how much God trusts in humanity but we either do not listen to his wishes or trust in Him, and because of this disobedience there are severe penalties. And this trend only continues throughout the bible. Abraham, on the other hand, conceded to his rules and does as he is told without even the slightest hesitation. He made his slow venture up the mountain, to the exact place God had shown him, and, builds the altar then ties his son up and getting him ready for the sacrificing (Gen 22:9). But at this point the Lord stopped him. Without shame, for he did as he was told, he announced â€Å"Here I am† (Gen 22 :11). This is unlike Adam whom has to hide himself for going against the Lords will earlier in chapter three of Genesis. And unlike in chapter three, instead of getting reprimanded and punished, Abraham is blessed by the Lord (Gen 22 :16-19), for he did what he was told even though it was a great loss in his family.

Closer to a Cure for Cystic Fibrosis Essays -- Proteasomes Cystic Fibr

Overcoming Proteasomes: One Step Closer to a Cure for Cystic Fibrosis Take a deep breath and consider how easy it was to do so. Now picture struggling and gasping for air everyday; normal, easy tasks to the average person prove to be quite challenging to a patient of cystic fibrosis. Scientists have always been daunted by this fatal genetic disease that affects the body by excreting a â€Å"thick mucus† in the lungs, making breathing difficult and blocking the â€Å"ducts† leading from the pancreas, causing â€Å"poor digestion of food† (1). Until recently, there was nothing that scientists could do to provide a long-term cure, but even though scientists cannot cure patients one hundred percent, they can increase their life expectancy. Despite having discovered the cystic fibrosis gene’s location in 1989, numerous underlying obstacles prevent complete success (2). The primary obstacle that prevents scientists from making gene therapy an effective cure is the placement of the healthy genes into long-term cells, the cells that remain long enough to be replicated. The replacement of the healthy gene into long-term cells is necessary because these cells make the new cells, thereby distributing the healthy DNA throughout the body. The properly functioning gene is attached to a vector or â€Å"carrying molecule† that will transport â€Å"the therapeutic gene to the patient’s target cells† (2). Currently, the most common vector is a virus because it can easily capture the gene and deliver it into the cell; the virus infiltrates the corrupt cells and places the healthy gene into the nucleus which then transforms the corrupt cell into one which operates properly (2). The only difficulty is that the body’s natural immune system provides many b... ...t-education/tips/ccysfibr.html>. 2. Institute NHGR. Gene Therapy [Internet]. 2007 [2007 September 18]; Available from . 3. Stefano Ferrari DMG, Eric WFW Alton. Barriers to and new approaches for gene therapy and gene delivery in cystic fibrosis. Advanced Drug Delivery Reviews 2002;64: 1373-1393. 4. J Kim C-PC, KG Rice. The proteasome metabolizes peptide-mediated nonviral gene delivery systems. Gene Therapy 2006; 12: 1681-1690. 5. Neil Campbell, and Lawrence Mitchell (1999). Biology. New York, Addison Wesley Longman, Inc. 6. Institute NHGR. Learning About Cystic Fibrosis [Internet]. 2007 [2007 September 18]; Available from: . 7. U Griesenbach DG, and EWFW alton. Gene therapy progress and prospects: cystic fibrosis. Gene Therapy 2007; 13: 1071-1077.

Machiavelli and Bush

In school, we came to know about Niccolo Machiavelli through his extremely popular statement, â€Å"The end justifies the means† (Machiavelli n.p.). Due to the unsavory reputation that has hounded Niccolo Machiavelli, the terminology Machiavellian is now utilized to describe a leadership style that is shrewd/cunning, deceiving/to be regarded with suspicion, as well as, ruthless/cold-blooded; a kind of leadership which is actually instituted upon â€Å"power politics† (Machiavelli n.p.). Political Action is an End Itself Furthermore, for some individuals who have read Machiavelli’s thoughts and ideas, they consider him as a â€Å"negative person†, sometimes he is even addressed as â€Å"somebody who is upholding evil and sin† (Machiavelli n.p.). In fact, the church considers him as immoral, unethical, and even evil (Machiavelli n.p.). This is because politics for Machiavelli should be taken as something which should not be blended with topics of religion, morality, as well as, ethics since politics he says is instituted upon its own value system (Machiavelli n.p.). For him, to evaluate political actions basing on religion or ethical standards is actually unwarranted (Machiavelli n.p.). Moreover, Machiavelli states that the end of the state is the acquirement/getting hold of, preservation, as well as, development/growth of authority/political power (Machiavelli n.p.). Comparing it to the other critical thinkers of the Machiavellian world, Machiavelli just do not consider this as â€Å"a means to an end† but an end in itself (Machiavelli n.p.). What he is saying is that if an act that’s motivated by politics leads to acquirement/getting hold of, preservation, as well as, development/growth of authority/political power then it is reasonable, understandable, and acceptable as well (Machiavelli n.p.). Similarities of Machiavelli and Bush This is where President Bush connects with Niccolo Machiavelli, President Bush believes that by annihilating the ruler, for instance, Osama Bin Laden and Saddam Hussein, he will be able to strengthen his hold and power and to bring about unity in the state and since that is the case, like Machiavelli, he believes that his action is justifiable (Thompson n.p). In addition to that, President Bush like Machiavelli feels that since they are the type of rulers who planned to get the better of, and to safeguard the state, then they will be eternally judged to be praiseworthy and be commended by everyone (Machiavelli n.p.). Last but not least, since Machiavelli believes that a ruler has to be cruel and ruthless if he has to; Bush patterned his attitude on that as well (Thompson n.p). He declared a war against Iraq which annihilated two hundred Americans working for the U.S. Armed Forces (Thompson n.p). Furthermore, his declaration also caused the death of countless Iraqi civilians, of which several are women and children (Thompson n.p). Added to that is the fact that such a war costs one hundred billion dollars, which if spent back home then will surely benefit more who are starving and are suffering from poverty (Thompson n.p). All of the above-mentioned entails a great deal of cruelty which should not at all occur in the first place (Machiavelli n.p.).   However, because, President Bush thinks that all these political actions he took are bound to cause the state to unite, then declaring a war even if it would cause countless deaths is still right and should not be negated or objected upon   (Machiavelli n.p.). Simply put, both President Bush and Machiavelli are similar basically on how they rule; to them, cruelty is justified as long as it will unite their state in the end (Machiavelli n.p.). Works Cited Machiavelli, Niccolo. The Prince. 1505. n.a. 16 April 2008. http://www.constitution.org/mac/prince.txt Thompson, Robert. n.d. n.a. 16 April 2008.                  

1993 Apush Essay

APUSH Essay Even though the Chesapeake Bay Colonies and New England Colonies would share ethnic roots they would differ greatly in their development. With New England’s society centered on religion and Chesapeake Bay’s around profit both came to the new world with their own intentions. Other aspects in which these societies differed was in economy and social structure. However regardless of differences and similarities both colonies would find their own way to thrive. When it comes to religion, the colony of New England was influenced to a much greater degree than Chesapeake Bay.Their whole reason for being there was because of religion. The main religious group in New England was the Puritans. The strict aspects of the Puritan way of life made the colony a very stable place to live. In comparison to the Chesapeake Bay Colonies where religion did not play a very big part there was not much political stability. The sect of Christianity practiced by the Chesapeake colonis ts was the Anglican Church. The Anglican Church was not nearly as strict or influencing on life as the Puritans’ practice.Without a strict set of rules in place from religion the only time the Chesapeake Bay colonies would enjoy stability in its early days would be under the military like rule from James Cook. The reason why religion usually would bring stability would be from the moral code embedded inside the teachings of the bible. From this people were able to humble themselves resulting in a stable society. Stability would eventually come to the Chesapeake Bay once it would become a royal colony.In addition to this tobacco would also become a major staple product for the Chesapeake Bay. Overall religion would be a bigger player in the development of New England as a colony. Economy was very different in both respective colonies. Economy in New England would be very simple. Mainly family units would each have their own farm in which they would become self sufficient on. O n top of this there would also be small local and international trade among New Englanders. Early on in the Chesapeake Bay colony was not very expansive.With a little bit of local trading with Indians the Chesapeake Bay colony would not have a big export until James Rolfe would bring tobacco to the colony. Tobacco would have a great impact on colony life. With the Crop being a very profitable export the plant would soon dominate the economy there. Soon however as exports increased the price would decrease the market would deflate. The tobacco market would breathe life into the Chesapeake Bay and also increase the amount of slaves needed to support the demand. Economy in both colonies although different would both manage to flourish in their own way.Social structure was also very distinct in both colonies. For instance Jamestown of Chesapeake Bay‘s population consisted mainly males upon its founding. Throughout its life men were discouraged to arrive in family units because of its harsh conditions. Also a hostile attitude towards Indian populations also stopped population in the colony to be self replenishing. Also altering its early development was the attitude of work from early settlers. Original settlers were of higher class and had distaste towards manual labor.Settlers would eventually grow past its original misgivings on manual labor and find economic stability from tobacco. In order to feed the labor needed to keep up with the tobacco industry indentured servants and then eventually African Slaves would find its place as a social class. Politically, the House of Burgesses was a form of self representative government in the colony of Virginia. Social Structure in New England was a bit more commonplace. Arriving in family units was much less discouraged and many small towns would pop up.With very local government life in New England was very structured. Family decisions were made by the father due to the patriarchal social structure. The big differe nces in social structure were very evident in American Colonial society. Overall despite their roots the Chesapeake Bay colony and New England were completely distinct societies complete with their own economies, religions and economy. Living life in both colonies offered a different culture unique to its area. In the end both would attribute to the diversity in life found on the east coast of colonial America