The resistance of a wire Essay Example for Free

The resistance of a wire Essay The results all proved to be so close together that it proves its not worth doing it for every measurement. Results 1 This table shows the results we took, with the length in centimetres running along the side, and the voltage along the top. The corresponding values in the table is the current, measured in Amps. I will now plot these results onto nine separate graphs and a final graph showing Length plotted against resistance. These results were taken in conjunction with Adam Cubbage. Each of us took part the taking of results. Final Results Length of Wire (cm) Resistance (? ) Analysing and drawing conclusions All these results and graphs show things about the relationship between Resistance and length of wire. The final graph shows an almost perfect straight line of results through the origin. This proves that resistance is directly proportional to the length of wire. If you look carefully on the graph you can see a slight change in pattern after the result for 50cm. This is due to the fact that results were taken over two lessons, the first 4 one day and the final 5 the next. The slight split could be due to a different set of equipment, slightly different components (different power supply etc. ) or even something as little as room temperature. If the results were taken over a single period of time I have no doubt there would be an absolutely straight line. The results also prove that doubling the length of wire, effectively doubles the resistance. For example if you look at the results for 20cm of wire (0. 8 and then the results for 40cm of wire (1. 6 you will see that the resistance for 40cm of wire is exactly double that of 20cm. All this evidence supports the prediction I made at the start, that the length of a piece of wire does indeed affect its resistance, and that there is a direct and proportional link between the two. Evaluation I think my results were fairly reliable and this was mostly thanks to the system of getting an average resistance from each length of wire, using a graph to average out the results. As I said before, there is a slight change in pattern after the result for 50cm. This is due to the fact that results were taken over two lessons, the first 4 one day and the final 5 the next. The slight split could be due to a different set of equipment, slightly different components (different power supply etc. ) or even something as little as room temperature. The equipment used over the two lessons may have differed slightly, e. g. the meters used to measure current and p. d. If the results were all taken in one go I have no doubt there would be an absolutely straight line. If you draw a line from the point of origin up to the fourth point you can see it is perfect, likewise if you draw a line from the fifth point on the graph to the ninth. I think this was a very suitable procedure and was certainly the most accurate way of performing this experiment. The only way I would improve it would be by taking all the results over a single period of time. This would avoid the split in the middle of the results. You could do another couple of different lengths but it wouldnt make much difference to the results. Just using the range that I have you can see all that you need to see to draw conclusions. I would like to try an identical experiment with a wire made of different material, just to see how different the results would be and then compare the two experiments. The real test for how accurate my results were is to calculate the Resistivity of my results and to compare it with the Resistivity that the wire should be. Resistivity is a property of a metal (whereas resistance is a property of a component). Resistivity does not depend on the dimensions of a component, only on the material from which it is made. We have done previous experiments to show that the resistance (R) of a conductor is directly proportional to its length (l) and is inversely proportional to its area (A). The diameter for the wire used was around 0. 8mm. To put this into a formula, where p is the Resistivity: R = pl A So: P (Resistivity) = AR l If we take the results for 80cm of wire we can work out the Resistivity of Constantan (the alloy wire we are using). In an A-level textbook I looked up the Resistivity of Constantan and discovered it should be 4. 9 x 10 -8 ? /m These two figures are fairly close and this indicates how accurate my experiments were.

Terrorism - Analysis of Pan Am 103 and the Tokyo Subway :: Exploratory Essays Research Papers

Lessons from Pan Am 103 and the Tokyo Subway      Ã‚   ABSTRACT: Terrorists were very active long before September 11. This essay reviews the 1988 downing of Pan Am Flight 103 over Lockerbie, Scotland and the March 1995 gas attack in the Tokyo subway. The results of these terrorist acts, who carried them out, how they were carried out, and what can be done in the future to prevent such incidents from happening again are all investigated.    On December 21, 1988 the world was shocked as a Boeing 747 Pan American Airlines flight from London's Heathrow Airport to New York City crashed in a fiery ball due to a terrorist-placed bomb in the forward luggage compartment. After the explosion the plane proceeded to break up into three different parts. The wings broke off separately, as did the main fuselage, and the first-class/cockpit area. All 259 people on-board, from twenty-one different countries, died, as well as eleven people of the town of Lockerbie, Scotland, where the plane was downed.    In a remarkably short amount of time after the crash hundreds of people were on the scene doing the initial investigative work that would eventually lead to finding the crash's cause as well as the perpetrators of the offense. Over one thousand police officers were dispensed on to the scene, over six hundred military personnel, morticians from the Royal Air Force, and teams of investigators from the Federal Bureau of Investigation, the Central Intelligence Agency, the National Transportation Safety Board, the U.S. State Department, the Federal Aviation Agency, the Boeing Company, and Pratt and Whitney. These people started surveying a land area that was seemingly too large to negotiate, 845 square miles. The United States also moved some of their extremely sophisticated spy satellites over southern Scotland to give the investigating teams high-resolution reconnaissance photographs of the area being searched.    The investigators were able to figure out fairly quickly that what brought down Flight 103 was a bomb, as it had all of the tell-tale signs, including no emergency or distress calls prior to the crash. The bomb had been concealed inside a Toshiba radio, which was placed inside a hard-sided Samsonite suitcase that had been designated as an unaccompanied bag. The suitcase had been transferred from an Air Malta feeder flight out of Valletta.    By June of 1990, six months after the

Intergumentary System

Integumentary System Laszlo Vass, Ed. D. Version 42-0280-00-01 Lab Report Assistant This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor. Purpose: What is the purpose of this exercise? The purpose of this exercise in to learn about structures and functions of the skin.Is there any safety concerns associated with this exercise? If so, list what they are and what precautions should be taken. As always take precautions when handling the microscope and slides and always have a clean safe work area. Exercise 1: Structures of the Skin Observations Before beginning, set up a data table similar to this Data Table 1. Fill in the names of the numbered st ructures. Skin Diagram (National Library of Medicine at http://nih. nlm. gov) Data Table 1: Structures of Skin| Item| Name| 1. | Hair shaft | 2. | Arrector pili muscle | 3. Sebaceous gland | 4. | Hair follicle | 5. | Sweat gland | 6. | Pacinian corpuscle | 7. | Subcutis (hypodermis) | 8. | Dermis | 9. | Epidermis | 10. | Sensory nerve ending | 11. | Dermal papilla | 12. | Sweat pore | Questions A. How does the skin tan when exposed to ultraviolet light? When ultraviolet light penetrates skin it begins to break down DNA causing the body to produce melanin. The melanin makes the body become darker or tanner and when the body is darker the more protected it is from the sun and sunburn. B. Describe the functions of the epidermis.The epidermis is the outermost layer that has keratinized squamous epithelium and the dermis. The epidermis has a bunch of different cells which allow it to perform many different functions. The keratinocytes produce keratin that produce fibrous protein that giv es skin protective properties while the melanocytes produce melanin to protect deeper cells from ultraviolet radiation and allows the skin to tan. Merkel cells from sensitive touch receptors on nerve endings and langerhans’ cells are involved in the immune response of the skin. Stratum basale constantly go through cell division to produce million of new skin daily. Stratum spinosum has think bundles of protein and stratum granulosum contain lipids that provide waterproofing for the skin. The stratum lucidum is a layer of flattened keratinocytes are only found in thick skin. Stratum corneum is the outer layer of the epidermis made of squished and flattened layers of dead keratinocytes. C. Describe the functions of the sweat glands. Sweat glands are controlled by sympathetic nervous system and regulate body temperature.When the body becomes to hot they secrete water to the skin surface and the heat is removed by evaporation. D. Compare the structure of the epidermis to that of the dermis. The epidermis consists of several different types of cells while the dermis canonists of dense, irregular connective tissue. E. Fill in the following table by either inserting the name of the structure/cell or by giving its function(s): Structure/Cell| Function(s)| melanocytes| Makes a pigment for tanning| Langerhans cells| Small and involved in the immune response| Merkel cells | Found on nerve endings|Stratum lucidum| Provides protection, thick found of palms a soles makes skin waterproof | Reticular layer | The blood supply here provides radiational cooling for the body| Exercise 2: Microscopic Structure of the Skin Observations Sketch and label your keratinized stratified squamous epithelium slide in the space below. Be sure to label all of the structures in the epidermis and dermis you were able to find: Questions A. Compare your slide to the photomicrograph example in the lab Procedure. How are they the same and how are they different?Propose a reason why you would see several differences between different slides of skin. B. What is keratin? Is fibrous protein that gives the skin its protective properties? C. Why is skin keratinized? Keratinized cells give skin a tough protective barrier. After a cell is born it begins to make protein called keratin that they store inside them. As the cells grow they build up with this protein until their so full they die forming a tough layer of packets of keratin. Exercise 3: Clinical Conditions of the Skin Questions A. What are the three types of skin cancer?Squamous cell carcinoma, basal cell carcinoma, and melanoma B. Which type of skin cancer is easily treatable? Basal cell carcinoma C. Explain why melanoma is so dangerous. Melanoma can spread to other areas of the body. D. What factors can cause acne? Acne is caused when sebum isn’t able to pass through the hair follicle. This causes cells from the lining of the follicle to shed to fast and clump together clogging up the follicle’s openi ng so sebum cannot get through. E. What is a common myth about the cause of acne?Eating chocolate, greasy food or dirty skin F. What are some treatments for acne? Dermatologists use a medication that reduces clumps of cells in the follicles, oil production, bacteria, and inflammation. Depending on the case of the acne the doctor may prescribe a topical medication or an oral medication. G. Describe the signs of first, second and third degree burns. First- affects only the outer layer, epidermis. Second- damage the epidermis and the dermis Third- involve damage or complete destruction to the fullest depth of the skin and underlying tissue. H. What are the principle effects of aging on the skin?

Machete Season - 1360 Words

3) Discuss the idea of forgiveness and guilt in Machete Season. In your paper, analyze how the men discuss the idea of guilt how they understand the concept of forgiveness. Consider: How do different men in the group understand guilt and forgiveness? Do the men feel guilt? Are you surprised by their sense/lack of guilt? Why are you surprised? How does Hatzfeld treat this topic? Philosopher Paul Ricoeur posed the question, how â€Å"can one forgive someone who does not admit his guilt?†(Hatzfeld 195) Whether this admission of guilt is enough to be forgiven or not, the â€Å"sincere† taking of responsibility for one’s actions is an absolute minimum in striving for forgiveness. Ricoeur’s question becomes especially relevant when discussing the†¦show more content†¦As Hatzfeld describes, these apologies are in many ways a â€Å"selfish act† because it facilitates the â€Å"diminishing of his offence and, thus, his punishment, even his guilt†(199). This is made clear in many of the interviews when discussing forgiveness, as the conversation often shifts to the discussion of the prisoners own problems such as Fulgence’s â€Å"shivery†(157) when thinking of his â€Å"prison future†, Elie’s dreams void of â€Å"the killed people†(162) but rather consisting of a return to his †Å"house†, and Pio’s desire to â€Å"assuage my memory†(160). Asking for forgiveness becomes a means to getting out of prison sooner, returning to family and friends sooner, and finally, to ease their own nightmares rather than concern for the victim’s own families, futures, and mental states. Comments like â€Å"He asked for forgiveness of everyone at his trial, and he still got a heavy sentence†(203) reflect the naà ¯ve and selfish attitude these killers have, not understanding the â€Å"extraordinary effort†(199) needed to forgive such horrific crimes. This selfishness is also reflected in to whom they are addressing, the next weakness in the sincerity of their apologies. Rather than asking the victims for forgiveness, the most effected by their actions, many of these prisoners seem to be more worried about receiving forgiveness from God, and protecting their own futures. Fulgence epitomizes this attitude when he claims that theShow MoreRelatedThe Rwandan Genocide And The Genocide1393 Words   |  6 Pagesan uneven distribution of status between themselves and the Hutu; explaining the chapter in Machete Season called â€Å"Suffering.† In this chapter, the killers (Hutu) use this as their cause behind not killing someone instantly, rather torturing them for their previous actions in positions of authority. The history of colonialism evident better explains not only the motives of the killers in Machete Season, but also the mindset behind why the genocide occurred. 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It is heart-wrenching to vividly be made aware of the torture this child had to undergo. Both Beah and Kamara describe what it is like to live under the cruel conditions of the war, and although these authors lived in similar worldRead MoreAnalysis Of Lizzy Axiak Rostrum Speech1014 Words   |  5 Pagesslavery. Sadly, all these debacles feature in the big picture. Two of the largest commodities which we buy almost weekly, clothes and chocolate, are causing the decay of human morality. How many of us overindulged in chocolate eggs, this Easter Season? I know I did. Alternatively, did you secretly indulge from Boxing Day on, even though Christmas had just finished and Easter still a long way to come? So when you bit into Hershey’s ‘strawberries n cream’ chocolate egg, are you sure that it wasRead MoreThe Book Things Fall Apart Essay986 Words   |  4 Pageswith a variety of problems. One troubling problem facing Okonkwo in the book is when his adoptive son is taken to be sacrificed. â€Å"He heard Ikemefuna cry, My father, they have killed me! as he ran towards him. Dazed with fear, Okonkwo drew his machete and cut him down. He was afraid of being thought weak†( Achebe, 44). Okonkwo does nothing to stop it; instead he kills his adoptive son whom he favored to show that, in his Nigerian culture, religious practice and justice overrules, and to surviveRead MoreHaitian Music: Rara Essay1668 Words   |  7 Pagesown 7 of 11 radio stations, and conversions to to Protestant Christianity. It is believed that about 15% of Haitians who identify with Christianity are Protestant. So, how does Rara fit into this rich cultural and religious history? Rara is a season of what appears to be young people parading very loudly through the streets in an effort to show off their musical ability; it is more than that. 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