Certain unknown wire Essay Example for Free

Certain unknown wire Essay To find out how resistivity changes as the length of wire is changed, and to find out the resistivity of a certain unknown wire. Equipment   Power Pack Ammeter Voltmeter   Crocodile clips   Wire   Metre rule Thermometer Method 1. Measure the diameter of wire using a micrometer, taking measurements in 3 different places along wire and take an average. 2. Take a piece of wire which is 100cm long, and attach t a metre rule. 3. Connect up wire to a power Pac, ammeter and voltmeter using crocodile clips and wires, to produce a circuit. 4. Vary the length of wire used in circuit by moving croc clips along the wire at 10cm intervals. 5. Record in a table the voltage and current for each of the 10cm intervals. 6. Find the resistance of wire for each recorded length, using the formula R= V/I 7. Repeat the whole method 3 times and find the average resistance of each length of wire. 8. Measure the temperature of the room with the thermometer and note this down. 9. Use the average diameter to calculate the cross-sectional area using A= ? (d/2)2 10. Plot resistance (y-axis) against length (x-axis). Draw in the line of best fit. 11. y=mx+c R= (? /A i length) + 0 Use gradient ? /A to calculate resistivity (? ). Safety. Safety was one of my top priorities. I was cautious when measuring the voltage of the wire incase it became very hot. The voltage was not increased to above 2V as this would probably burn my hands or the metre rule, due to the heating effect of wire. Preliminary test It was necessary to carry out a preliminary test in order to familiarise with using the equipment, and also to help realise mistakes, so that they wouldnt affect the real experiment. The experiment was set up as said so in my method. Preliminary Results Length of wire (m) Average resistance (? ). My results show me that as the length of the wire increases so does its resistance. In my actual experiment I will get 3 sets of results and calculate average in order to obtain precise readings. I found that I should use a low voltage in order to keep the heat generated as low as possible. Using a very high voltage could have burnt the wire or the lab unit. During the experiment the wire heats up, this causes more collisions between the electrons and the atoms as the atoms are moving into the path of the electrons. This increase in collisions means that there will be an increase in resistance. So to eliminate this extra resistance I will have to turn the power pack off after a while to let the wire cool down. I would also need to ensure that the crocodile clips were placed in the exact positions on wire e. g. 10, 20 cm etc. this would ensure reliable and more exact results. All these will have to be taken into account and will help me to minimize errors when calculating the resistivity of my unknown piece of wire. Prediction I predict that as the length of the wire increases, so too will its resistance. 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. So if the length is doubled the resistance should also double. This is because if the length is doubled the number of atoms will also double resulting in twice the number of collisions slowing the electrons down and increasing the resistance. My graph should show that the length is proportional to the resistance. Resistance means the property of anything to constrict the flow of electrons (a current). The electrons that carry the energy within the metal wire collide with obstacles (atoms) inside the wire and change direction. (The atoms in the wire are obstacles to the electrons. ) This is known as scattering. This causes electrical resistance. Therefore, I can predict that the electrons will collide with the atoms, when the atoms have more energy, more often. The graph that I am expecting should look something like: Theory We define the resistance of a material as resistivity. 2 factors affect the resistance of a conductor are its length and its cross-sectional area. Resistance ? Length (Doubling length doubles resistance) Resistance ? 1 Area (Doubling the cross-sectional are halves the resistance) Resistivity can be measured using ? = AR L And R= ? L A Where: R = resistance P= Resistivity constant L= Length A=Area To find ? I am going t plot a graph of R against L. The gradient of the graph will allow me to calculate ?. The equation of the straight line is y= mx + c As the line will go through the origin c =o Therefore y= mx The Resistance will be the y-axis and Length will be the x-axis. Therefore:- R= mi L As R= ? L The gradient of this is ? /A (excluding R and L) A So.. m=? /A ?= mA The area will be found by measuring the wires diameter and using the formula A=? (d/2)2 Section B- Results L (cm) VThe diameter of the wire was found using a micrometer. 1/mm 2/mm 3/mm Average/mm 0. 19 0. 19 0. 19 0. 19 Minimising Errors To minimise errors the following precautions were taken:   Method completed 3 times so that averages could be calculated. All results taken at same time so that temperature changes do not affect resistance Micrometer used to measure diameter of wire, as it can measure small distances accurately Meter ruler used to measure wires length accurately. Power pack was turned off to cool inbetween readings so that the wire did not get hot and thus affect the reliability of my results at each value.   I also tried to minimise human error in the experiment, such as putting the crocodile clips on the exact lengths and recording the readings on the ammeter and voltmeter accurately. Section C- Analysis Calculation The cross sectional area of the wire is calculated using: A= ? (d/2)2. So my value for resitivity of the wire according to my results is 39 i 10-8 My prediction was correct because I got a straight line on my graph and this shows that the length is proportional to the resistance and as the length of wire increases so does its resistance. I believe my experiment was good because Section D- Conclusion Analysis of errors Error in the area of the wire 1/mm 2/mm 3/mm Average/mm Range/mm 0. Possible sources of error Systematic errors   There may be inaccuracies in the measuring equipment. Its possible that the micrometer may have been damaged and may not have read the thickness of the wire accurately.   There may have been an error in measuring the location of the crocodile clips, and this may have lead to inaccurate results.   The voltmeter takes a small amount of current from the wire Random errors The temperature of the wire and the room may have lead to increased or decreased resistances.   Thickness of the wire would not be constant, this would lead to different resistance values in different parts of the wire. Unknown material of wire   The power supply may not have been constant. Improvements   Errors in meters- use 3 different meters to check current, and voltage values   Location of crocodile clips- use pointers instead of clips to get accurate measurements Some current flows through the voltmeter- I could have used an oscilloscope as it has a very high resistance so current will not go through voltmeter.

PULLMAN Essay -- essays research papers

The Town of Pullman: Success or Failure? The invention of the railroad was probably the most important occurrence in the nineteenth century. The United States became a unified front and interstate travel become safe, cheap and efficient. Industries related to the railroad began to prosper, fueling much of the American economy. Entrepreneurs quickly began to take advantage of this boom and thus â€Å"American Big Business† was born. George Pullman was one of the many prominent tycoons of this â€Å"Railroad Era†. Through the use of his talented ingenuity and high organizational skills, he acquired a vast fortune and immense power. George Pullman is most notably credited for the creation of the Pullman Sleeping Car. Its invention enhanced the pleasure of railroad travel by making it more comfortable, clean and exciting. As George Pullman’s invention gained quick public approval, his company began to expand at an enormous rate. This presented a great deal of proble ms to Pullman. â€Å"The company wanted to increase efficiency and economy in servicing and providing cars by spreading facilities. He [Pullman] wanted several hundred acres adjacent to railroad and water transportation.† In 1868, Pullman decided on the Calumet region in southern Chicago. Pullman selected the Calumet region because it offered â€Å"cheap land, low taxes, and excellent transportation.† Few people knew his second and main intention was to build a model town adjacent to the new factory, which he hoped would improve his business enterprise. Pullman was deeply troubled by the social problems of the mid- nineteenth century. He believed that they were the root of the labor unrest his company was experiencing. â€Å"The period showed a dramatic intensification in the numbers of the urban poor, as people with little capital and few useful skills came to the cities in search for employment.† Living conditions were terrible and congestion, dirt, and poor s anitation were held responsible for diseases. Crime, prostitution and violence were blamed on poor housing while alcoholism became synonymous with the slum. Many attributed the poverty and the poor living conditions of the working class to â€Å"the lack of such virtues such as frugality, industriousness and temperateness.† It was believed that the general solution to the problem of the workingman and his family was to elevate their character. Through Pullman’s experience ... ...n social planning and happiness for the individual. A town is recognized for the individuals who live in it, not the business it seems to incorporate. Pullman had a disillusioned, egotistical regard for his workers. When asked about his intentions on building the model town, he commented: â€Å"Capital will not invest in sentiment, nor for sentimental considerations for the laboring class. But let it once be proved that enterprises of this kind are safe and profitable and we shall see great manufacturing corporations developing similar enterprises and thus a new era will be introduced in the history of labor.† Pullman never seemed to grasp how a workingman’s happiness must be fulfilled on a much deeper level than his mere physical settings. The leisurely enjoyment of oneself as well as an overall establishment of identity was the key. When Pullman planned his model town, it was a dream which he envisioned for himself. A dream which would increase his wealth, improve his business and make him renowned. In his heart, he might have never intentionally wanted to socially deprive his work force; it just so happened that the planning of the town did not take this into proper consideration.

Attrition Rate in It Industry Essay

According to human resource experts, the average attrition rate is projected to grow at 31 per cent in Indian firms in the April-June quarter, a rise of 9-10 per cent from the preceding quarter (January-March). SPECIAL: Best companies to work for India In the April-June quarter of 2011-12, the average attrition rate was 27 per cent. Generally, employees would have received their annual appraisals during the April-June period and those not happy with their performance review or salary hikes seek better opportunities. Consequently, attrition rates are seen going up in these three months, experts opined. â€Å"In the current quarter, we are expecting an average attrition rate of 30 per cent. In Q4 employees were not keen to switch jobs due to appraisal season. Now in April they reached on higher salary compared to previous one and have a chance to negotiate for better salary with new employer along with new appraised designation,† MyHiringClub.com CEO Rajesh Kumar said. â€Å"Salary and designation are the major factors for higher attrition outlook in Q1, FY13. One more concern is having in employees mind if they’ll change their job in this quarter they are entitled to enter into appraisal cycle with their new employer also. So they are not going to loose anything with job change,† he added. Another HR consultant Ripples Consultancy Services CEO and MD Rishi Raman said. â€Å"We would see a high attrition rate of 30-31 per cent in the first quarter of the current fiscal. The reason behind such attrition is many employees are not satisfied with their appraisals. â€Å"A good performer did not expect 10-15 per cent of hike, their expectation is not less then 20 per cent,† he added. Experts said that attrition would be in double digits in all the sectors. It would be highest in the IT/ITeS sector at 31 per cent, followed by telecom (26 per cent), banking and financial services (23 per cent), aviation and hospitality (22 per cent ), real estate (15 per cent), FMCG (21 per cent), automobile and manufacturing (19 per cent). HR consultants are of the view that employers needs to take various steps in order to retain talent like providing career opportunities and suitable work environment as high attrition impact the company’s resource negatively. â€Å"One of the most effective way to ensure good working conditions for your employees is to provide them with advancement opportunities,† Raman said. HeadHunter Solution Director Priyanka Pawar said,† the high attrition costs increases the costs to the organisation considerably. â€Å"The more the people leave an organisation, the more it is a drain on the company’s resources like recruitment expenses, training and orientation resources and the time. The high attrition rate also affects the productivity of the organisation,† she added. High attrition rate hits IT companies’ bottomlines TNN | Aug 26, 2010, 12.44AM IST CHENNAI: Bad things happen in good times too. Indian IT companies are finding it hard to recruit and retain employees as the recovery takes a definite shape. And their bottomlines are getting hit due to rising wages and high attrition. Earnings before interest, tax, depreciation and amortisation (EBITDA) margins or operating margins have been dipping for most of the IT biggies in the recent quarters largely because of the spurt in wage inflation. Operating margins of Infosys Technologies declined by 2.36% in June quarter compared with the March quarter. Tata Consultancy Services (TCS) and HCL Technologies saw their operating margins falling by 0.7% and 1.1%,  respectively. This slide is not an aberration. The companies’ EBITDA has been on a decline for the past four quarters. On the attrition front, a report by Motilal Oswal, a financial services firm, said that Wipro leads the pack with 23% attrition, followed by Infosys (15.8%), HCL Tech (15.7%), and TCS (13.1%) in the June quarter. The figures have been increasing for all these companies for the past few quarters.

Essay on Pride and Prejudice Book Analysis - 1352 Words

In Jane Austen’s England, British heritage, it was said that â€Å"we certainly know the world of the English late 18th century and the Regency beginning the 1800s was very different from our own. Her novels of love and social manners in the Regency gentry are loved because of her brilliant use of language and her savvy insight into human motivation and relationships.† (1) The book, â€Å"Pride and Prejudice,† by Jane Austen takes place in England around the 1800s.The setting itself is what sets the mood, tone, and emotions in which is displayed within each character. During this historical time period, women had limited roles. Roles in terms of abilities to interact socially with others. Jane’s motive to have written these stories is to portray†¦show more content†¦Most of the characters in the story marry some point in the book. Property inheritance in the book, Pride and Prejudice, becomes a major factor between the relationships between the tw o families. Mr. Bennett failed to see and search for an intelligent wife. Mrs. Bennet had limited morals, social position, dignity, and lacked caring for her husband and kids. The main two characters, Elizabeth and Darcy, are both trying to find love. But, Elizabeth (protagonist) wants someone special. She describes it as the complete opposite of Darcy. Darcy (antagonist) isnt necessarily a bad guy, he’s just arrogant and prideful. Elizabeth is just prejudice against people like Darcy. This book was originally named, First Impressions, because of that very reason. As soon as Elizabeth officially got to know and understand Darcy her opinions towards him changed. Which later falls in love with Mr. Darcy and marries him. Darcy is a Byronic hero; he is very arrogant, intelligent, and sensitive. He also has a disfavor for social settings and struggles with integrity.They become extremely passionate with values better than others; therefore, arrogant. 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Namely, the book and the title reflect the division between individual as a spontaneous self and individual as socially constructed part of a greater whole, and the interaction that takes place as a result of the interaction between these selves. â€Å"Pride,† while it can be informed by the presence of others, is a character trait that can exist individual qua individual. For example, compares â€Å"pride† to â€Å"vanity,† a word with