Balance Sheet Essays - Generally Accepted Accounting Principles

Balance Sheet Although the balance sheet was first implemented just a couple of centuries ago, it has quickly developed and sophisticated to become nowadays a widely used and powerful tool in the hands of professional users, well known and popular even among the mass public. In spite of its prominence, or may be because of it, the balance sheet can not be easily and fully described in a few words, but still, if we leave aside its various functions and forms and any other subjective factors, we can state that the balance sheet is a summary of an enterprises' assets, liabilities and equity at a specific moment of time. To simplify this description even further we could say that the balance sheet shows an entity's possessions, obligations and others' debts to it. The "objective" point of view however is often too restrictive, and the most simple things many times prove to be rather complex... Among the thousand more complex definitions appended to the balance sheet one of my favorites is the definition given by .... according to which the balance sheet is a statement meant to communicate information about the financial position of an enterprise at a particular point in time, summarizing the information contained in accounting records in a clear and intelligible form, giving information about the financial state of an enterprise and indicating the relative liquidity of the assets, showing the liabilities of the enterprise (i.e. what the enterprise owes and when these amounts will fall due), able to assist the user in evaluating the financial position of the enterprise, being however only part of the data needed by users. Or to summarize this long description with which I completely agree, I could say that although the balance sheet is one of the most outstanding instruments in the hands of financial analysts, managers, investors and other users, its importance should not be over emphasized, it has to be viewed along with many other documents, and it is far from being the perfect and the "super" financial document. In order to get a more clear, complete and fair picture of the balance sheet, apart from reviewing the definitions given by the experts in this field, we would need to consider as many sides and issues of the subject as possible. Being objective we should have a look at the etymology of the word "balance", the history of this document, its theoretical essence and the basic concepts of accounting implied in it, its forms in the accounting practise. In our attempt however not to become "over-objective" or scholastic, we should also review the aims and purposes of the balance sheet and the extent to which they are fulfilled, the users of this financial statement and their contradictory needs, the negative aspects and restrictions of the balance sheet, and finally the trends of its further development. In short, we have to go further into the matter... The history of the so called financial statements, and the balance sheet among them, can be traced back to Renaissance Italy, where along with the double - entry book - keeping they first evoked to respond to the growing more and more complex needs of the accounting connected with the economic development of the society at that period (expansion of trade activities, development of banking, etc.) and with the transition from the owner - manager model towards limited companies or the breakdown of ownership from control. Obviously these historical events called for the development of new methods and new documents, reflecting the changes. Naturally the word "balance" itself has also an Italian origin ("bilan", "bilanz") though it is formed up of two latin words: "bi" - double and "lanx" - scales. Even from here it becomes obvious that the balance sheet is a sheet or summary of two different aspects of one and the same thing: an entity's financial position. Further to this aspect, we can take a look at the definition of the balance sheet given by John Arnold, Tony Hope and Alan Southworth: "The balance sheet is the most inituitive and easily understood document of accounting. Most of us at some stage in our lives will be required to compute a listing of our possessions. Such a listing of possessions is a major element in the construction of a balance sheet.". Far from being a precise statement on what the balance sheet is, it can easily be perceived from a phylosofical and psychological view point, and then, though defined at present times, it can be related with the historical side of the balance

Grenvilles novel The Secret River Essays

Grenvilles novel The Secret River Essays Grenvilles novel The Secret River Paper Grenvilles novel The Secret River Paper Essay Topic: Everything Is Illuminated Our identity in a community is determined by one’s own internal emotional view of humanity. This is shown in Steven Herrick’s prose novel The Simple Gift, Tim Winton’s novel Breath and Kate Grenville’s novel ‘The Secret River’ through the use of the young disparate protagonists throughout these texts we can observe and extract many adaptations made by personas to survive in a changing world and different meanings of belonging and not belonging. Within the texts we observe individuals gaining a sense of connection and security to other people through literature and imagination. Individuals need role models in order to develop a reciprocal connection with others, by fostering a sense of identity and develop self-esteem. However the consequences of not achieving t2his relationship leads to loss of identity. Individuals must make choices between different places, communities and other people who offer them different concepts of belonging. . 2. 3. The aspect of individuals needing to gain a sense of connection and security through literature and imagination is illuminated through Tim Winton’s Breath and Steven Herrick’s The Simple Gift. In Steven Herrick’s The Simple Gift this connection to literature is shown through the protagonist Billy with the use of the quote ‘and I’m there, on the island, /gorging on tropical fruit,/trying to decide/whose side I’m on’ in this quote Herrick’s alludes to William Golding’s ‘Lord of the Flies’, this analogy depicts Billy integrating into the novel and deciding which side of society he wishes to assimilate into to, deciding whether or to abide by ‘normal’ customs or challenge rules of society’s expectations. This extended metaphor shows how having a lack of structure or authority leads to chaos and isolation. : Similarly, in Winton’s novel this aspect of literature is shown through the quote â€Å"I liked books – the respite and privacy of them – books about plants and the formation of ice and the business of world wars. Whenever I sank into them I felt free† The use of first person, emotive language of ‘liked’ shows that individuals gain a sense of connection and imagination through literature, art and imagination. Winton uses listing as well as diction, with the use of such words like respite and privacy imply safety and security in ones imagination, this allows the protagonist ‘Pikelet’ a getaway from reality and feelings of not belonging. Individuals need role models in order to develop a reciprocal connection with others, fostering sense of identity and develop self-esteem. However not achieving this relationship leads to a loss of identity. In Steven Herrick’s The Simple Gift, the reciprocal relationship between the personas Old Bill and Billy are shown through the quote ‘I knew that Old Bill was giving/ me more than these keys I held. / holding someone’s past in my dirty hands. ’ This symbolism of the keys is used to illuminate the depth of Billy’s relationship with Old Bill and the concept of belonging represented by a physical house. This shows Old Bill’s trust in Billy because Old Bill is not only giving Billy a house, he is giving him a part of his life along with removing the degrading tag of homelessness. This is also seen in the quote â€Å"two hobos laughing/laughing the morning away†, Herrick’s use of repetition of laughing shows the stable, down to earth relationship between the pair and their deep security placed within each other. The hyperbole of ‘laughing the morning away’ as well as the colloquial language of ‘hobos’ enlightens the reader to admire the mindset of the homeless protagonists. 8. Similarly, this is shown through the protagonist featured in Breath, Pikelet, after his mentor Sando abandons him. â€Å"I went numb. I couldn’t say what it was and didn’t dare try. How do you explain the sense of being made to feel improper? † Tim Winton has manipulated the use of a rhetorical question to highlight Pikelet’s insecurities that have consequentially developed as a result of an upbringing in an isolated town. Winton’s use of diction, using the word ‘improper’ shows us that Pikelet doesn’t belong in his ‘given’ social group. The colloquial language gives the persona Pikelet a more authentic voice, creating a relatable protagonist. Winton has also used the quote ‘, ‘Sando paddled up and held my hand like a brother or a father. ’ Winton’s simile compares the difference between Sando, and Pikelet’s father who was never there to encourage and support Pikelet during his adolescence, this creates and emotional connection and dependence on Sando, both authors create to relationship to use the depends and mutual addiction on a role model 9. 10. Finally, Individuals must make choices between different places, communities and other people who offer them different senses of belonging. This is shown by Winton in Breath again through the persona Pikelet when he said â€Å"Everything around me seemed so pointless and puny/ Wherever I went I felt like the last awake person in a room full of sleepers†, this simile is used to show Pikelet’s search for belonging and people he could associate with, but not realising the countless barriers in Pikelets unique personality. In contrast the use of diction in the quote ‘we feel like we naturally belong at the beach, others detest it because they feel alien to it. ’ Shows that Pikelet knows where he belongs and whom he belongs with. 1. Similar shown in the extract of Kate Grenville’s ‘The Secret River’ through the convict protagonist William Thornhill with the quote ‘For them, Home was nothing but a story. If they were to go to London they would be outsiders’, this metaphor illuminates the choice he must make to uproot his family back to England, even though they have develop a connection to a physical place, it shows they want Australia to be like London. Capital of Home emphasises the significants . The repetition of home throughout the extract is used. Also shown by the hyperbole in ‘Had often been on the wrong side of the wall’ alluding to the wrong side of society, it is also seen as it relates to prison society, feeling trapped and isolated, just like in Australia. In conclusion both the composers have identified that belonging within a community is determined by ones childhood and background and the role of parental figures and role models, this is achieved through the use of adolescent protagonists as well as relating connection a to literature, enabling individuals to escape to another reality, the composer also highlight the need for role models and belonging in communities to enhance ones sense of humanity.

Knowledge Workers and the Brooklyn Bridge 8 Essay

Knowledge Workers and the Brooklyn Bridge 8 - Essay Example engineers, namely Washington Robeling and those who worked with him, that were mainly concerned with design aspects such as knowledge of gradient, impact of erosion by water over time, angles for rafters and columns and related information. Designing and construction of a bridge requires a basic knowledge and comprehension of the many aspects constituting â€Å"optimum structural and mechanical performance.† (Fertis, xiii). In the case of a highway bridge, dynamic and vibration analysis that needs to be carried out requires knowledge of the basic properties of the materials and cables that are used to build the bridge. Such knowledge of material properties is then used in performing the static and dynamic analysis, in developing a bridge design that is safe as well as functional. The static and dynamic analysis will involve calculations to determine both static and dynamic deformations of the bridge, together with its frequencies of vibration. This will also involve conclusions to be drawn on how long the bridge span should be in order to ensure that its rigidity is maintained in a safe design. Hence a knowledge worker working on the design and construction of the bridge in Robeling’s day would also have required a basic knowledge of statics, mechanics and structural mechanics. A knowledge worker would thus need to be acquainted with basic engineering concepts in designing of bridges. Communication in those days when the Brooklyn Bridge was first built centered around personal contact, hence these were restricted to light signals and Robelais passing on his communications through his wife. As a result, workers had to possess communication skills in interacting with members of their teams, most of whom were likely to have been drawn from the same local area of New York and largely comprising immigrants. But the kind of communication systems being used in the present day is also different from those existing during the time of Robelais. Knowledge workers may

Teenage drug addicts Essay Example | Topics and Well Written Essays - 1250 words

Teenage drug addicts - Essay Example A study by National Center of Education Statistics during the year 2009 found out that the main reason of this proliferating numbers of teen drug addicts is that 22% of high school teens are being provided in drugs in their respective schools (Russell, 2008). This teen population, around 45% of this part of teen population cannot see any ‘risk’ due to excessive drug use. That means lack of awareness is the dominant reason that has led to such a grave issue. Teens living in UK are also in the running. They too fall in the same category that is severely attacked by this issue of Drug Abuse. They too are falling in the trap and ruining their lives, UK’s society and the country as a whole. Teen Drug Addiction in UK – Causes, Effects and Current Trends Even after the government’s several attempts of implementing strict policies on its teen population, the numbers of ‘Teenage Drug Addicts in Britain’ are increasing at a high rate. The deaths i n Britain due to drug abuse rose from 1952 to2182 deaths in total. Before peeking into the world of Teen Drug addicts in UK, we first need to know who these drugs came into this country and ruined the lives of many people, enjoying their teenage life. In case of Cocaine, UK is considered to be the most affected country due to drug abuse in the entire world. With 2% regular users of cocaine in UK, teens living between these people will surely fall in this trap and try their first drug, and this is what really happened. With a 19million share of the cost of drugs in the GDP of UK, more than 40% of this is paid by the UK teens. These figures clearly demonstrate the scenario of drug addicts who are teenagers and are living in Britain (Plant, et al, 2010). Overview of Teen drug Addiction During the time 2008 to 2009, around 8.1% increase has been observed in the number of teen drug users in UK. In UK, drug abuse is not just an epidemic, but a plaque. United Kingdom has a long history of teen drug abuse in its regards, because it was the first ever country of European Union that was reported to see the emergence of the drug misuse. In United Kingdom, drugs are commonly supplied around the country that’s why teens cannot find difficult in finding them and becoming huge big drug addicts in a short time period. This has led to a creation of social norm about this country as now the teen population have become really open minded when it comes to use drugs openly in social gatherings (Paylor et al, 2012). The current scenario of teen drug addicts in Britain has illustrated that this issue is getting out of hand. In a European Schools Survey Project, with 42% teen boys and 39% teen girls, illegal drugs have been used. Alcohol abuse, alcohol one of those drugs widely used in teenagers in UK, is prevailing commonly in UK, and this situation is getting worse in case of girls. Professor Martin Plant, of the University of West of England said: â€Å"One of the big prob lems is that vast numbers of young people who engage in these behaviors believe that they are completely invulnerable†. Causes of Teen Drug Addiction One of the reasons of a high rate of teenage drug addicts in UK reported by this professor are poor parenting. Parents living in UK are very broad minded and don’

History of Nursing Research Worksheet Essay Example for Free

History of Nursing Research Worksheet Essay Nursing Research covers key issues, including health promotion, human responses to illness, acute care nursing research, symptom management, cost-effectiveness, vulnerable populations, health services, and community-based nursing studies† (Henly, 2013). Sigma Theta Tau Journal published by this organization is now called Image—The Journal of Nursing ScholarshipFirst published: 1967 Importance: â€Å"This widely read and respected journal features peer-reviewed, thought-provoking articles representing research by some of the world’s leading nurse researchers. Reaching health professionals, faculty and students in 90 countries, the Journal of Nursing Scholarship is focused on the health of people throughout the world. It reflects the society’s dedication to providing the tools necessary to improve nursing care around the world† (Hegyvary, 2011). Research in Nursing and Health First published: 1978 Importance: â€Å"a general peer-reviewed research journal devoted to publication of a wide range of research and theory that will inform the practice of nursing and other health disciplines. It has influenced on nursing education administration, health issues related to nursing, and testing research in practice† (Research In Nursing Health , n. d. ). Western Journal of Nursing Research First published: 1979 Importance: â€Å"The dissemination of research studies, book reviews, discussion and debate, and meeting calendars, all directed to a general nursing audience. It has risen to the challenges of the ever-changing nursing research field, providing an innovative forum for nurse researchers, students and clinical practitioners to participate in ongoing scholarly debate† (Conn, 2013). Scholarly Inquiry for Nursing PracticeFirst published: 1987 Importance: â€Å"Research and Theory for Nursing Practice (former named Scholarly Inquiry for Nursing Practice) focuses on issues relevant to improving nursing practice, education, and patient care. The articles strive to discuss knowledge development in its broadest sense, reflect research using a variety of methodological approaches, and combine several methods and strategies in a single study. Because of the journals international emphasis, article contributors address the implications of their studies for an international audience† (Springer Publish Company, 2013). Applied Nursing ResearchFirst published: 1988 Importance: â€Å"To present original, peer-reviewed research findings clearly and directly for clinical applications in all nursing specialties. Regular features include ‘Ask the Experts,’ research briefs, clinical methods, book reviews, news and announcements, and an editorial section. Applied Nursing Research covers such areas as pain management, patient education, discharge planning, nursing diagnosis, job stress in nursing, nursing influence on length of hospital stay, and nurse/physician collaboration† (Applied Nursing Research, 2013). Nursing Science QuarterlyFirst published: 1988 Importance: â€Å"Nursing Science Quarterly (NSQ) is a peer-reviewed quarterly journal publishing original manuscripts focusing on nursing theory development, nursing theory-based practice and quantitative and qualitative research related to existing nursing frameworks, contributed by the leading theorists, researchers and nurse executives† (Nursing Science Quarterly, 2013). Conduct and Utilization of Research in NursingFirst published: 1982-1983 Importance: â€Å"The Conduct and Utilization of Research in Nursing (CURN) project, an organizational approach, was designed to develop and test a model for using research-based knowledge in clinical practice settings† (Morse, 2006). Annual Review of Nursing ResearchFirst published: 1983 Importance: â€Å"The purpose of this annual review is to critically examine the full gamut of literature on key topics in nursing practice, including nursing theory, care delivery, nursing education, and the professional aspects of nursing. ARNR has brought together internationally recognized experts in the fields of nursing, and continues to deliver the highest standards of content and authoritative reviews of research for students, researchers, and clinicians† (Springer Publishing Company, 2013). AgenciesEstablishment date and goal or function: American Nurses’ Association (ANA) Council of Nurse Researchers Established: 1972 Goal: â€Å"The Council of Nurse Researchers helped with the development of research endeavors, gave credit to meritorious research, and facilitated the discussion of research ideas† (Burns ; Grove, 2009). National Institute for Nursing Research (NINR)Established: 1993 Goal: â€Å"NINR is to promote and improve the health of individuals, families, communities, and populations. NINR supports and conducts clinical and basic research and research training on health and illness across the lifespan to build the scientific foundation for clinical practice, prevent disease and disability, manage and eliminate symptoms caused by illness, and improve palliative and end-of-life care† (National Institute Of Nursing Research,

Human Cloning Essay -- Ethical Issues, Cloning

Human Cloning Human Cloning comes with two dangerous processes, reproductive cloning (the creating of a new organism) and the therapeutic cloning (the creation of a new tissues or â€Å"other biological products†) which affects the ethics of human society. Scientists perceive cloning benefits all men and women, while religious leaders stress the idea of cloning to be an unethical process. Although human cloning serves as an aid to the children and parents with conflicts, cloning is completely unacceptable to convey human life as a product. Humans reproductively and therapeutically give the idea of people becoming a product rather than a living being. Siedler emphasizes that â€Å"reproductive cloning could also represent an enormous step in direction of transforming human procreation into human manufacture† (Siedler 91-92). In other words, reproductive cloning will create a world full of dolls that will remove every trace of living beings. Though it is hard to believe the world becoming a doll house for each family or community, it has come to a conclusion that the ability of cloning and â€Å"creating children† is questioning every person, â€Å"what does it mean to be a human?† (Yount 114). If it was not bad enough for this world to describe some of the people to be looked upon as nothing but a thing, cloning pushes the idea to a whole new level. â€Å"By opening the door to many things such as manipulation,† Yount states, as she desperately explains the fear in cloning, â€Å"of wanting to be someone else, it can treat them as objects instead of person,† (Yount 114). To even add the intensity of what cloning could do, therapeutic cloning delivers a new definition to fear. According to the ... ...). Parents suffer the mental issue of the child recieving â€Å"medium-term consequences including premature aging, immune system failures, and sudden unexpected deaths,† (Siedler 87-88). Therapeutic cloning sounds safe and ethical, â€Å"but it is no different from those that could be used in attempts to create cloned children† so why risk the process? (â€Å"Cloning† 94). Therapeutic and Reproductive cloning is used in a beneficial way in different circumstances, but the disadvantages overpowers the beneficial usage with the risk of corrupting the world and more. Reproductive cloning forms human manufacturing as well as a child to a parent who are unable to bear one, and therapeutic cloning give animals a repaired heart muscle, as well as the corruption of religion and social ideas in this world. Cloning comes with consequences and more are to come, so is it worth to clone?

Atomic Structure

The Rutherford Model of the Atom 1. In 1911 Rutherford proposed the nuclear model of atomic structure. He suggested that an atom consists of a central nucleus (where most of the mass of the atom is concentrated) having a positive charge, surrounded by moving electrons carrying negative charge. Geiger and Marsden carried out an experiment to verify his proposal. The Geiger/Marsden a Particle Scattering Experiment 1. The apparatus is illustrated in the diagram below. | 2. The apparatus was in an evacuated container. The detector was a ZnS screen observed through a low power microscope. Each time an alpha particle hit the screen, a small flash of light was produced. 3. The detector was mounted on a support such that it could be rotated to measure the angular deflection of the alpha particles as they passed through a very thin sheet of gold. They measured the numbers of particles deflected through various angles. 4. It was found that most of ? particles pass through the gold undeflected; only a relatively small number are deflected (scattered). 5. Their results were considered to confirm Rutherford’s model and allowed them to estimate the size of the nucleus (greater than 10-14m) and the size of the atom (greater than10-10m), thus producing the slightly surprising conclusion the most of the space occupied by an atom is empty space! Closest Approach of an Alpha Particle to a Nucleus 1. For a given speed of alpha particle, the closest approach to a nucleus, rmin, will occur when the initial direction of motion of the particle is along the line joining the centers of particle and nucleus. 2. In this case, at the point of closest approach, the speed of the particle is zero. 3. As the particle approaches the nucleus, kinetic energy is being converted to electrical potential energy. K. E. lost = E. P. E. gained| 4. Electrical potential at a distance r from a point charge Q is given by | 5. For a nucleus of atomic number Z, the charge is Ze, where e is the magnitude of the charge on one proton (the same as the magnitude of the charge on an electron). 6. The magnitude of the charge on an alpha particle is 2e 7. Therefore, the energy, w, possessed by an alpha particle placed at distance, rmin, from a charge Ze is given by | 8. So, we have | which gives | Millikan’s Experiment to Measure the Charge on one Electron 1. The diagram below is a very simplified representation of Millikan’s apparatus. | 2. Small drops of oil were allowed to fall into a region between two metal plates, (the top plate had a hole in it). 3. Some of the drops became charged by friction. Further ionization was caused by a beam of x rays. 4. Millikan measured the terminal speed of a drop as it fell through the air, with V = 0. From this he could calculate the radius of the drop (and hence it’s mass). He then applied a voltage, V, to the plates and measured the new terminal speed of the same drop. 5. The change in the terminal speed of the drop was used to calculate the magnitude of the charge on the drop. 6. When many measurements had been done, all the charges were found to be integral multiples of a basic unit of charge, assumed to be the charge on one electron. 7. The value, e, is approximately -1. 6? 10-19 C. 8. A simplified version of Millikan’s experiment can be done by finding the voltage needed to just hold an oil drop stationary between the two plates. 9. Consider a drop having a charge q and mass m. | 10. If the drop is stationary, then the two forces acting on it have equal magnitudes. where E is the field strength. 11. Now, , where d is the distance between the plates, Therefore The Electron Volt (eV) 1. The electron Volt is a unit of work (or energy) much smaller than the Joule. 2. If 1electron moves through a potential difference of 1V then 1eV of work is done. Relation between the Joule and the electron Volt 1. Potential difference is work done per unit charge so, . 1 J is the work done when 1C moves through a p. d. of 1V. 2. The charge on one electron is -1. 6? 10-19 C. 3. Therefore 1eV is the work done when 1 ·6? 10-19C moves through a p. d. of 1V. This means that . 4. To convert energy in J to energy in eV, Experiment to measure the Charge to Mass Ratio of Electrons 1. The method proposed here is similar to that used by J. J. Thomson in 1897. Electrons in an evacuated tube (a â€Å"cathode ray tube†) are sent towards a region of space where there are electric and magnetic fields at 90 ° to each other. If the field strengths have a particular ratio then charged particles can pass through them undeflected. | | | 2. In the following analysis | | | V = voltage accelerating the electrons and producing the electric field between the plates| | v = speed of the electrons| | m = mass of one electron and e = charge on one electron| | E = electric field strength (E = where d = distance between plates)| | B = magnetic flux density| 3. If the electrons pass undeflected (magnitude of electric force equal to magnitude of magnetic force), then it can easily be shown that | 4. To find the speed of the electrons, remember that during acceleration the electrons are losing electric P. E. and gaining K. E. | | E. P. E. lost = K. E. gained| eV = 5. Therefore, | | | 6. Combining equations 1 and 2 to eliminate v gives, | | | | 7. Thus, using his experimental apparatus, Thomson was able to determine the charge-to-mass ratio of the electron. Today, the accepted value of is C kg-1. Atomic Structure The Rutherford Model of the Atom 1. In 1911 Rutherford proposed the nuclear model of atomic structure. He suggested that an atom consists of a central nucleus (where most of the mass of the atom is concentrated) having a positive charge, surrounded by moving electrons carrying negative charge. Geiger and Marsden carried out an experiment to verify his proposal. The Geiger/Marsden a Particle Scattering Experiment 1. The apparatus is illustrated in the diagram below. | 2. The apparatus was in an evacuated container. The detector was a ZnS screen observed through a low power microscope. Each time an alpha particle hit the screen, a small flash of light was produced. 3. The detector was mounted on a support such that it could be rotated to measure the angular deflection of the alpha particles as they passed through a very thin sheet of gold. They measured the numbers of particles deflected through various angles. 4. It was found that most of ? particles pass through the gold undeflected; only a relatively small number are deflected (scattered). 5. Their results were considered to confirm Rutherford’s model and allowed them to estimate the size of the nucleus (greater than 10-14m) and the size of the atom (greater than10-10m), thus producing the slightly surprising conclusion the most of the space occupied by an atom is empty space! Closest Approach of an Alpha Particle to a Nucleus 1. For a given speed of alpha particle, the closest approach to a nucleus, rmin, will occur when the initial direction of motion of the particle is along the line joining the centers of particle and nucleus. 2. In this case, at the point of closest approach, the speed of the particle is zero. 3. As the particle approaches the nucleus, kinetic energy is being converted to electrical potential energy. K. E. lost = E. P. E. gained| 4. Electrical potential at a distance r from a point charge Q is given by | 5. For a nucleus of atomic number Z, the charge is Ze, where e is the magnitude of the charge on one proton (the same as the magnitude of the charge on an electron). 6. The magnitude of the charge on an alpha particle is 2e 7. Therefore, the energy, w, possessed by an alpha particle placed at distance, rmin, from a charge Ze is given by | 8. So, we have | which gives | Millikan’s Experiment to Measure the Charge on one Electron 1. The diagram below is a very simplified representation of Millikan’s apparatus. | 2. Small drops of oil were allowed to fall into a region between two metal plates, (the top plate had a hole in it). 3. Some of the drops became charged by friction. Further ionization was caused by a beam of x rays. 4. Millikan measured the terminal speed of a drop as it fell through the air, with V = 0. From this he could calculate the radius of the drop (and hence it’s mass). He then applied a voltage, V, to the plates and measured the new terminal speed of the same drop. 5. The change in the terminal speed of the drop was used to calculate the magnitude of the charge on the drop. 6. When many measurements had been done, all the charges were found to be integral multiples of a basic unit of charge, assumed to be the charge on one electron. 7. The value, e, is approximately -1. 6? 10-19 C. 8. A simplified version of Millikan’s experiment can be done by finding the voltage needed to just hold an oil drop stationary between the two plates. 9. Consider a drop having a charge q and mass m. | 10. If the drop is stationary, then the two forces acting on it have equal magnitudes. where E is the field strength. 11. Now, , where d is the distance between the plates, Therefore The Electron Volt (eV) 1. The electron Volt is a unit of work (or energy) much smaller than the Joule. 2. If 1electron moves through a potential difference of 1V then 1eV of work is done. Relation between the Joule and the electron Volt 1. Potential difference is work done per unit charge so, . 1 J is the work done when 1C moves through a p. d. of 1V. 2. The charge on one electron is -1. 6? 10-19 C. 3. Therefore 1eV is the work done when 1 ·6? 10-19C moves through a p. d. of 1V. This means that . 4. To convert energy in J to energy in eV, Experiment to measure the Charge to Mass Ratio of Electrons 1. The method proposed here is similar to that used by J. J. Thomson in 1897. Electrons in an evacuated tube (a â€Å"cathode ray tube†) are sent towards a region of space where there are electric and magnetic fields at 90 ° to each other. If the field strengths have a particular ratio then charged particles can pass through them undeflected. | | | 2. In the following analysis | | | V = voltage accelerating the electrons and producing the electric field between the plates| | v = speed of the electrons| | m = mass of one electron and e = charge on one electron| | E = electric field strength (E = where d = distance between plates)| | B = magnetic flux density| 3. If the electrons pass undeflected (magnitude of electric force equal to magnitude of magnetic force), then it can easily be shown that | 4. To find the speed of the electrons, remember that during acceleration the electrons are losing electric P. E. and gaining K. E. | | E. P. E. lost = K. E. gained| eV = 5. Therefore, | | | 6. Combining equations 1 and 2 to eliminate v gives, | | | | 7. Thus, using his experimental apparatus, Thomson was able to determine the charge-to-mass ratio of the electron. Today, the accepted value of is C kg-1.