Resistance of a wire Essay Example for Free

Resistance of a wire Essay We undertook an experiment to find the relationship between resistance and a length of wire. Equipment: Variable resister, Wire 1m long, Digital voltmeter, Digital ammeter, 4 X 1. 5 cell, 1m ruler, Connecting wires. Method We collected our equipment needed and set it out as the circuit diagram below. I started by drawing out my results table to record my results on. The headers for the columns where as follows: Length (cm), Current (A), Potential difference (V) and Resistance (I). At every 10cm we took a reading and entered it into our table. Some flickered between two values so I took both down. Starting at 1m and working down. On the second experiment I started at 10cm and worked the other way to see whether it affected the results. When using the variable resistor we kept it on the minimum resistance throughout the experiment. While taking the results we had more than one result for the current and potential difference, which in turn caused some results to have more than one resistance value. Because of this I had to alter our table slightly during the experiment to ensure we took down all the results. To ensure the test was as fair as possible I repeated the test to ensure the experiment was fair and true. Looking at my results in the table they are very similar which proves that it was fair. Results These tables show my results from the experiment and the sum for: V I R First experiment: Length (cm) Current (A) Second reading for (A) Potential difference (V) Resistance ? (I) Second result for (I). Second experiment: Length (cm) Current (A) Second reading for (A) Potential difference (V) Second result for (V) Resistance ? (I) Second result for (I) Third result for (I) Fourth result for (I) I have drawn graphs for these results: see appendix a and b. Analysis My results show that the resistant relates to the length of the wire used. As the current increases the potential difference does and the resistance decreases. As the length of wire is reduced the potential difference reduces and so does the current. There is a slight difference between our first and second experiment. Both graphs show that there is a definite pattern but there are some anomalies. The anomalies seem to be separate from the other results. But this anomaly happened on both experiments on 60cm. There may be some other reason for this. I cannot see why it should happen on both sets of results at the same measurement. Both graphs are similar and follow a very similar line. Graph A shows quite a straight line with only one less extreme anomaly where as graph B show a reasonably straight line with one major anomaly which stand out considerable from the rest. On both graphs the results take a wavelike form rather than a straight line. The results do to an extent follow Ohms law. On graph A, 4 of the plots run on the same line, which agrees with Ohms law, and graph B 4 plots do the same. The second graph started at a lower current and potential difference but I think it should be higher because of the use of the wire before which could have increased the temperature. On the second experiment there was more flickering on the ammeter and voltmeter, which caused the increase in the results. Although the flickering occurred it was constant. On table 1 the potential difference decreased in shorter stages that table 2. When plotting my results on a graph I had to take an average from my results. Conclusion Current id the flow of electrons around the circuit this is pushed by voltage. The resistance tries to oppose it. This is apparent from looking at our experiment results. The resistance stays constant as long as the component does not change its physical condition i. e. The wire does not get hot. George ohm was the first scientist to investigate this theory. The resistance is measured in Ohms Resistance at a constant temperature is proportional to potential difference. The relative size of the voltage and resistance decides how bit the current will be. By increasing the voltage more current will flow but by increasing the resistance the current is less. This is shown in our results. Our results agree with the theory. 100cm of wire = little current but a lot of P. D = lots of resistance 10cm of wire = lots of current but little P. D = little resistance This shows the longer the piece of wire the more resistance Wires of different material have different resistance: Copper wire I Steel wire V The graph shows above that cooper wire has a low resistance and is a good conductor. Steel has a higher resistance and a lower conductivity. Both wires have the same potential difference (voltage) across them. Wire A. I Wire B Wire C V As you can see above different wires have different resistance. Evaluation There were a few problems that occurred in our experiment such as the flickering of the ammeter and voltmeter, which caused us to have to take more than one result. On both graphs there was an anomaly on 60 cm. There may be some other reason for this. Both graphs are very similar and follow a very similar line. Graph A shows quite a straight line with only one anomaly where as graph B show a straight line with one major anomaly which stand out considerable from the rest. On 60cm the potential difference increased on both sets of results. The temperature of the wire was not taken to see whether it had increased in temperature during the experiment. It does not show increased resistance on the second table, which was taken straight after the first experiment, which could have affected it. By taking the temperature of the wire on the same resistance for a period of time we could see how long it takes for the temperature to increase and in turn for the resistance to increase. This could help with evaluating our results and also time the experiment to see how long the wire had current flowing through it and then if it had increased in temperature. The results are reasonably reliable because the do to an extent obey Ohms law. I think the reason for the unreliability could have been because the wire had changed its physical condition (got hotter). To further our investigation we could go on and use a longer piece of wire 2m and also use different types of wire such as steel and copper. Change the temperature of the wire because wire that is colder is a better conductor. I believe our results were reliable but need improving by the suggestions I have given above. Bibliography Hodder and Stoughton AQA GCSE Physics Class notes   CPG Revision and Practice Guide Alison Eatock GCSE Physics 30/11/03 Resistance of a wire 1 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

Cards of Fortune :: Free Essays Online

Cards of Fortune I suppose in a way Tonia is right, life isn’t worth living, if both of us aren’t there to see it, together. That’s what twins do after all. They are an intrinsical part of each other's life, ceasing to exist without the second. But, I feel that we’re drifting apart, separated by this something, intangible, unnamable, and yet more potent than all of our past put together. I can remember how as little girls we played together. There were no other children with the troupe, and even when we passed the towns†¦ well, the children were never friendly, preferring to fear and call names. But Tonia, she was always there to play with, to laugh with, to cry with. Playing by the fire, dancing under the moon, we were eccentric children, not given to the usual childhood games, preferring instead to talk quietly, and whisper our secrets, but it was always us, together, until now. One of our favorite games was to confuse Septemius, the poor man; he always did have trouble telling us apart. But then, we were children at the time, and not given over to worrying about the troubles of a grown man. Poor, dear, Septemius, even now I can sense his thoughts, and he’s worried, as I am. He knows that Tonia is growing apart from us, and every so often, I’ll catch him looking at her, realizing the distance that’s growing, between her and me, between all of us, and I see that look of daunting sadness in his eyes. I think he sees mother in her, in us rather. I remember the look he gives her now, and it’s the look he had when my mother†¦ left. People tend to think children do not remember such things, that in their happy naà ¯ve lives they don’t understand, but I knew then, as I do now, that mother broke his heart. And as much as Septemius grieves for Tonia’s departure from the family, and through that grieves still for the loss of the woman he once knew, so do I grieve. And, yet, somehow I feel my sadness deeper, a sharper pain, for it is not the loss of an abstract family member, or even a sister, it is the loss of part of myself.

Allegory of the Cave Essay

Written as a dialogue between Glaucon (Plato’s brother) and Socrates (his mentor), The Allegory of he Cave is a poem composed in approximately 1509. The source of this poem is from series on Plato called â€Å"The School of Athens† by Raphael. Socrates had a specialized teaching method (now referred to as the Socratic method) which was characterized by asking and answering questions in order to stimulate critical thinking (EH 72). The structure of this piece reflects this method because Socrates is using dialect and a series of questions to teach the lesson/metaphor. An allegory can be defined as a story, picture, or poem that, when interpreted, has a hidden meaning/lesson. This allegory has to do with a cave in which prisoners are being held captive. They are chained to the floor with their heads only facing one wall, therefore they are unable to see what is behind them. Though this is an allegory because the cave represents life and the puppeteers behind he prisoners making shadows represents reality. The hidden meaning of the allegory stems from the idea that the prisoners have a misinterpreted idea of reality. They only see the shadows and reflections that the puppeteers are making therefore they believe that is life. Once they turn around and it is revealed that those were puppeteers the whole time, they are extremely shocked. It shows us that our perception of reality and what we see around us is false. Our imperfect interpretations of reality may not always be what they seem, sometimes we are viewing what we want to view, seeing what our mind want’s us to see, rather that seeing the true reality. The theme explored in this allegory has connections tied back to the cultural themes of the Hellenic Age and ancient Classical Greek Philosophy. People viewed the enlightenment as a new coming of age in which new teachings were applied. This poem represents the teaching of morality in a time where philosophers were striving to teach of the world around them (EH 84). During the Hellenic period the ancient Greeks were undergoing great  cultural and political change. The love for art and literature rose as ancient Greeks were moving from oral to a literate culture form based on rational thought, which can be exemplified in the poem The Allegory of the Cave. During the Hellenic Age (EH 83), Greek cultural influence was high and the spreading of the arts, literature, philosophy, politics, and education was wide spreading throughout Europe. The Hellenic Age held a high value on learning. Athens held a numerous amount of libraries and philosophy during the time experienced many new and de veloped schools of thought (EH 76). This is viewed through the allegory because it is trying to teach the world a lesson through the use of philosophy. The primary form of art during this period was sculpture and the dominant form of literature was poetry, as again exemplified by the allegory. I personally found the allegory difficult to understand at first, thought after a couple of careful reads of the reading material I began to see the true meaning. I found the allegory to be very interesting and morally informative. I do agree with the ideas it expresses to the extent that it makes a person revisit how they perceive the world around them and the true meaning of reality. I do not believe it should go as far as to change your mindset to question whether you are viewing a true reality or just a mental paradox. Though overall I believe I learned a lot from his allegory and despite the difficulty, thoroughly enjoyed reading it.

Reaction Of Martin Luther Kings Letter From A Birmingham...

â€Å"Letter from a Birmingham Jail† Reaction â€Å"We know through painful experience that freedom is never voluntarily given by the oppressor; it must be demanded by the oppressed.† In 1963, Martian Luther King Jr was protesting for blacks to have equal rights in Birmingham, Al. The city administration found out about these protests and ordered the police to arrest them. Now in jail was confronted by a court and ordered not to protest in Birmingham. In response King wrote what is now known as the â€Å"Letter from a Birmingham Jail†. The letter is considered to be the most important documents of the civil rights movement as it explains Kings strategy of using nonviolent protests to make a point and spark a negotiation. Kings letter started the†¦show more content†¦King then enacted the nonviolent campaign that consisted of four steps. First off, he investigated if injustice exists. This was easily noticed as court and police refused to investigate the bombing of the black homes. The black leaders were mo stly encored by the city’s leaders. Second, he proceeds to negotiate this didn’t go over well. As merchants promised to remove the white and colored signs. The signs soon returned most likely the merchants were treated by the court and the KKK. This leads to the third step; the process of self-purification. The process got the black people in non-violent mindset to accept blows without fighting back and endure a jail cell. The last step was then set in motion direct action marches and sit ins were in full swing. This created tension in society that would eventually lead to the wall surrounding the negations to crack and fall to the ground. This plan worked for King in every city he visited. King explains what a just and unjust law is as â€Å"justice too long delayed is justice denied.†. For 340 years the blacks were denied their constitutional rights as the color of your skin was not mentioned in this great document. Unfortunately, the government pushed segregation in the class rooms therefore many black people had no idea the constitution existed. Not even children could understand why they were denied entry into public places and why white people hated them. Black people lived in constant fear. A law must follow a moral guildShow MoreRelatedLetter from a Birmingham Jail Analysis1025 Words   |  5 Pagesâ€Å"A Letter from Birmingham Jail† by Martin Luther King Jr. was written in the margins of a letter posted by the clergymen of Alabama at this time that sparked his interest and while he inhabited the jail cell for parading around without a permit. This time allowed him the ability to respond wholeheartedly to this cynical oppressing. King’s le tter addresses specific points presented in the Clergymen’s and this direct response distinguishes King’s strong points through his powerful writing.   UnethicalRead MorePersuasive Speech : Dr. Martin Luther King, Jr.1334 Words   |  6 PagesIn any good speech, the most important part of the speech is not what is said during the speech, but what the audience feels and remembers after the speech was over. Dr. Martin Luther King, Jr., a powerful advocate of African American rights, was an expert at convincing his audience to feel and react to his speeches however he wanted them to. One of the main ways he achieved this was through the use of the artistic proofs. The ‘artistic proofs’ is a term coined by the ancient greek philosopherRead MoreLetter from Birmingham Jail; Rhetorical Analysis Essay1620 Words   |  7 PagesMartin Luther King Jr.’s Use of the Rhetoric Triangle Every writer has some sort of drive when writing a piece of work. Whether that drive comes from a creative source or the need to prove a point, it exists. For Martin Luther King Jr. that drive was the need to put an end to racial injustice that seemed to be everywhere. Martin Luther King Jr.’s â€Å"Letter from Birmingham Jail† is a perfect example. â€Å"Letter from Birmingham Jail† was King’s response to eight clergymen’s â€Å"A Call for Unity.† His driveRead MoreMartin Luther King’s (Mlk) â€Å"Letter from Birmingham Jail† Argument Analysis1432 Words   |  6 PagesKyle McCrite Ms. Vaughn English 102-01 14 September 2009 Someone Else’s Shoes Martin Luther King’s (MLK) â€Å"Letter from Birmingham Jail,† was written in 1963 as a response to the Eight Alabama Clergymen’s public statement against King’s actions in April of that year. Martin Luther King Jr. was an activist for desegregation of the south in the early 1960s and overcame much adversity to attain incredible gains on the segregation issue in the United States. 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In this letter, we hear Dr. Kings honest opinion about the criticism he received from his opponents of timely protest. We gain a lot of insight about Kings honest opinion about his political motivations of his movements and why he felt that it was critical to act when he did. Another movementRead MoreRhetorical Analysis Of Martin Luther King Jr s Letter From Birmingham Jail1831 Words   |  8 Pageseffective when all three rhetorical appeals, Logos, Pathos, and Ethos, come together to form an indisputable argument. Dr. Martin Luther King Jr and Malcolm X are two of the most influential figures of the past few decades; similarly, their work is summarized as some of the most persuasive and controversial of all time. The audience of both of their pieces, â€Å"Letter from Birmingham Jail† and â€Å"The Ballot or the Bullet† include oppressed African Americans and the white oppressors themselves. Each man takesRead MoreLetter From Birmingham Jail Essay Essay1451 Words   |  6 PagesZhuo Liu Lauren Sassenoff English 1P-5 25 September 2016 Letter from Birmingham Jail Essay In 1963 Martin Luther King Jr. wrote a letter while incarcerated in Birmingham jail to eight clergymen in response to their letter known as â€Å"A Call for Unity.†Ã‚  The letter asked for the stop of direct action type protest in Birmingham, Alabama that Martin Luther King was leading.   The letter has become known as one of the greatest works of argument in American history. Part of the reason for the letter’sRead More Henry David Thoreaus Civil Disobedience and Martin Luther Kings Letter from Birmingham Jail820 Words   |  4 PagesHenry David Thoreaus Civil Disobedience and Martin Luther Kings Letter from Birmingham Jail Henry David Thoreau and Martin Luther King, in â€Å"Civil Disobedience† and â€Å"Letter from Birmingham Jail,† respectively, both conjure a definitive argument on the rights of insubordination during specified epochs of societal injustice. Thoreau, in his enduring contemplation of life and its purpose, insightfully analyzes the conflicting relationship between the government and the people it governs. He consideratelyRead More The Letter from Birmingham Jail Essay1029 Words   |  5 PagesOn April 16, 1963, from a jail in Birmingham, Alabama, Martin Luther King Jr. composed an extensive letter to eight clergymen who condemned the timing of the civil rights movement. Although the letter was addressed to these eight clergymen, the Letter from Birmingham Jail speaks to a national audience, especially King’s â€Å"Christian and Jewish brothers†(King, 29). His peaceful but firm letter serves as a remarkably persuasive voice to an immensely chaotic mess, a nd is seen as a major turning point