Ethical Practice in Social Work

Ethical Practice in Social Work The aim of this assignment is to demonstrate links between different codes defining ethical practice, legislation and the requirements of professional conduct. The author will also discuss knowledge of traditional social work values and recent changes in the value base of social work. The relationship of ethical themes and the range of ethical theories will also be considered, concluding with the requirements of professional social work practice. Although social work is a profession laden with contradictions, the primary task within the social work profession is to ensure that the directives and principles enshrined in social work ethics, call on social workers to establish human rights and willingly be able to challenge unjust principles (Allan et al 2009). Moral codes and social structure is recorded as far back as the Ancient Greek Polis era with suppression of civic autonomy. The idea of life of virtue and human fulfilment leading on to the new course in ethics chartered during the Hellenistic era are the most discussed social structures discussed to date, regarding early ethics and values although forms of social structural developments were occurring in Egypt, Mesopotamia, China and India has less recorded by historians (Bryant 1996). Bisman (2004) acknowledges that the core concept of moral concerns drove social works development during the professions formative years. Although Jones (1997) cited in Bisman (2004) (pg: 110) complains that â€Å"the profession has been particularly silent over the past twenty years about the shifting patterns in social wellbeing and disadvantage† and that this silence may be a direct violation of the social work codes of ethics. The emphasis of social change was more evident during the settlement movement and the emphasis was on Toynbees philosophy that there was a need to unite the advocacy of social reform and the inclusion of various classes to ensure society performs those duties (Bisman 2004). Self determination is central to the social workers ethical responsibilities to clients. Hepworth et al (2009) (pg: 60.) predict that â€Å"codes of ethics are the embodiment of a professions values†. Acknowledgment for principals and standards for social workers behaviours are imbedded in the Codes of Ethics circulated by the National Association of Social Workers addressing the range of responsibilities that social workers have as professionals to their clients, colleagues, employers, profession and to society as a whole (Hepworth et al 2008 ). Addams (1902) (pg: 1) â€Å"believed that ‘ethics is but another word for â€Å"righteousness† without which life becomes meaningless†. The United Nations Convention on the Rights of a Child acknowledge that the values vary from country to country and the understanding of values universally are very problematic. However, it is not just the question of different values, but a question of relative power (Heintz 2009). Every Child Matters (2003) contains five outcomes which are being healthy, staying safe, enjoying and achieving, making a positive contribution as well as economic well-being have absorbed the UNCRC Articles into a comprehensible table. This ensures that practitioners are drawn to reflecting the ethical principles and value base when making their decisions regarding client needs. Wilks (2005) highlights that there are two central conceptual strands that account for social work values; these are social work ethics and anti-discriminatory practice. However although these two strands lie together there are conflicts. Strategies have been adopted to bridge the gap in principle by means of social justice or equality. Nash (2000) was also interested in the ethics of the individual self and understanding the power differences. Although seeing everyone as social actors, concerned with interaction through social behaviour can at times be fragmented, unstable, fluid and fast changing. This unpredictability is why it is very important that social workers analyse each individual case thoroughly, reflecting on where and when to employ ethical and value based decisions that will influence positive results. Clarks (2000) cited in Tovey (2007) acknowledges that there are five basic principles that promote ethical practice in social work are: Respect for and promotion of individuals rights to self-determination Promotion of welfare or well-being Equality Disruptive justice Discipline Furthermore, it is important that traditional social work values are employed, but it is also important that consideration for limitations of traditional social work values and how these values change at macro, meso and micro levels of practice. Dominelli 2004(pg: 63) argues that although empowering clients is seen as a way of moving forward, â€Å"it is unable to do more than deal with issues at the micro level of practice in the practitioner-client relationship, and has little impact on structural inequalities, which also need to be ended†. By being involved in transforming the knowledge base and structure of clients current or future situation, the social workers has to rethink the epistemological base on which social work is founded and establish a value base that aims to create a professional culture that can guide particular interventions (Dominelli 2004). Banks (2006) acknowledges that ethical issues are problematic in social work and that the codes of ethics and codes of conduct fail to explicitly address issues faced by those who are regulated by them. Practioner`s find themselves in difficult situations which at times results in ethical dilemmas. It is still imperative to meet the requirements of professional conduct and that the deontological approach creates a logic whereby professionals are duty-bound to follow their ethical code and where ethical practice without guiding principles is inconceivable (Gray 2009 pg: 2). The Scottish Social Services Codes of Practice (SSSC 2005) 2005 are a key step in a system of regulation for social services delivered along with setting standards for practitioners to be accountable for their actions. SSSC (2005) state that there are six codes of practice that social service workers are required to take account of these are: Protect the rights and promote the interests of service Users and carers. Strive to establish and maintain the trust and confidence of Service users and carers. Promote the independence of service users while protecting Them as far as possible from danger or harm. Respect the rights of service users whilst seeking to ensure that their behaviour does not harm themselves or other people. Uphold public trust and confidence in social services. Be accountable for the quality of their work and take responsibility for maintaining and improving their knowledge and skills. Social work has undergone radical changes, in addition, the imperialistic approach has been highly criticised as being stereotyped and culturally preoccupied with the blame culture. Raynor (1984) recognised that there was a difference in accountability, regardless of justification. His findings were that social workers are accountable for their own actions, although social workers were only protecting the weaker party in an imbalance of power. It is important that social workers draw on empirical approaches, although the focus should be on solving problems and narrowing the problematic gap in cultural differences between social worker /client relationship working within a moral rational manner. A postmodern approach in social work has highlighted areas in the welfare state that acknowledge that specific welfare resources are being cut due to rationalisation. Social services need to look at the way economic, social structures and regional injustices in impoverished communities are constructed and adapt to meet their individual needs. Postmodernism argues for the ‘grand or ‘universal social change on which social work was founded, but now ultimately social work must refocus its attentions on exposing global economical inequalities and oppressive gender and ethnicity-based relationships across the globe (Noble 2004). The Kantian philosophy encourages that we should treat others as a being who has choice and desires along with a being is those who are capable of rational thought and self determined actions should have the ability to make decisions and act accordingly to their own choices and desires (Banks 2006). Although deontological and utilitarian approaches tend to dominate social work ethics Lovat and Gray (2008) dispute that within this postmetaphysical age Habermas offers a form of proportionate ethics through the Aristotelian and Thomistic thinking offering a new and practical approach which is particularly appropriate to a modernately post-scientific, postmetaphysical age. Lovat and Gray (2008) (pg: 1101) also recognised within the moderately post-scientific age, although the thinking had a heavy reliance on science they were â€Å"aware of the limitations of science in addressing adequately all of lifes demands and providing all of its answers†. Lovat and Gray (2008) also proposed a new approach to ethical deliberation and judgment that has potential to meet the needs of those seeking greater ontological certainty than science can provide. By implementing a Proportionism approach, which is an ethical and moral approach and holds promise for a more balanced perspective in that social work is both science and art. Overall the proportionist approach is comfortable with the inconsistent position in any ethical dilemma and by applying wisdom, commonsense and probing scientific explanations an ethical decision can be made. â€Å"The value of a proportionist position is best captured when we realise that any ethical decision which runs counter to accepted or popular norms cannot be underestimated in terms of its potential to create tension, fear or recrimination†( Lovat and Gray 2008 pg: 1107). Changing Lives (2006) highlights the ethical and value base by means of four tier approach negotiating a balance between care and control, although the practitioner is under statutory obligation and the nature of the situation is complex the focus should be with avoiding any ethical boundary disputes working in a multi disciplinary approach focusing on the value base work with the client. Pitts (2000) discusses the Federation International des Communautes Educatives 1998 (FICE 1998) describes that a sound ethical practice is of critical importance. A code of ethics establishes good practice and offers guidance to individual workers in difficult situations, along with acting as a template against which to test conduct and target reform of modifications that need to be made. This in turn guides the practitioners to think about best practice and new answers to ethical issues that may arise. Within Getting it Right for Every Child (2006) Big Words and Big Tables section 2.6 Consent/Ethics, ethically empower the child or young person regardless of age to educate and promote the best services available by informing the chid or young person of all resources available. The FICE 1998 is dedicated to promoting the lives and future of children and young people around the world creating and promoting global standards for looked after children, The British Association of Social Workers has a Code of Ethics key principles reinforce what service providers should be doing to meet the needs of children and young people these are: Human Dignity and Worth Respect for human dignity and for individual and cultural diversity Value for every human being, their beliefs, goals, preferences and needs Respect for human rights and self-determination Partnership and empowerment with users of services and with carers Ensuring protection for vulnerable people Social Justice Promoting fair access to resources Equal treatment without prejudice or discrimination Reducing disadvantage and exclusion Challenging the abuse of power Service Helping with personal and social needs Enabling people to develop their potential Contributing to creating a fairer society Integrity Honesty, reliability and confidentiality Competence Maintaining and expanding competence to provide a quality service Harris (1998)(pg: 843) highlights that â€Å"in the new social services departments, social work was to exist, not simply as another branch of local authority administration, but in its own right as a state-mediated, bureau-professional labour process†. Consideration for Biesteks casework principles, individualisation, purposeful expression of feelings, controlled emotional involvement, acceptance, non-judgemental attitude, service user self-determination and confidentiality were the early foundations of principles that have paved the way for influencing present date values in social work (Banks 2006). Tovey (2007) insists that the principles are open to interpretation and practitioners should be aware of the limitations in ethical decision making and the focus on rules and duties influence determining actions in particular situations. The legal framework within the Children (Scotland) Act 1995 (Act 1995) underpins what practitioners are required to do to ensure children and young people are provided for and looked after by parents, guardians or their local authority. The Act 1995 chapter 36 section 19 advises that the plan for services has to take into consideration relevant services to be provided. References Addams, J. 1902. Democracy and Social Ethics. Macmillan: London. Allan, J., Briskman, L., Pease, B. Critical Social Work: Theories and Practices for a Socially Just World. Allen Unwin: NSW. Banks, S. 3rd Ed, 2006. Ethics and Values in Social Work. Palgrave Macmillan: Basingstoke. Bisman, C. 2004 Social Work Values: The Moral Core of the Profession. British Journal of Social Work 2004. 34, 109-123. Bryant, M,J. 1996. Moral Codes and Social Structure in Ancient Greece: A Sociology of Greek Ethics from Homer to Epicureans and Stoics. New York Press: USA. Available on line: Changing Lives: Report of the 21st Century Social Work Review http://www.scotland.gov.uk/Publications/2006/02/02094408/8 [Accessed October 2009]. Available on line: Children (Scotland) Act 1995 http://www.opsi.gov.uk/ACTS/acts1995/ukpga_19950036_en_3#pt2-ch1-pb2-l1g19 [Accessed October 2009]. Dominelli, L. 2004. Social Work: Theory and Practice for a Changing Profession. Polity Press: Cambridge. Available on line:Every Child Matters (2003) http://www.dcsf.gov.uk/everychildmatters/strategy/strategyandgovernance/uncrc/unitednationsconventionontherightsofthechild/ [Accessed October 2009]. Available on line:Getting it Right for Every Child (2006) http://www.scotland.gov.uk/Publications/2005/06/20135608/56098 [Accessed October 2009]. Gray, M. 2009. Moral Sources and Emergent Ethical Theories in Social Work. Brittish Journal of Social Work, September 22, 2009.1-18. Harris, J. 1998. Scientific Managment, Bureau-Professionalism, New Managerialism: The Labour Process of State Social Work. British Journal of Social Work. (1998) 28, 839-862. Heintz, M. 2009. The Anthropology of Moralities. Berghahn Books: United States. Hepworth, H, D., Rooney, H, R., Rooney, D,G., Strom-Gottfried, K., Larsen, J. 2009 8th Ed. Direct Social Work Practice: Theory and Skill. Cengage Learning: Canada. Lovat, T., Gray, M. 2008. Towards a Proportionist Social Work Ethics: A Habermasian Perspective British Journal of Social Work 2008.38, 1100-1114. Raynor, P. 1984. Evaluation with One Eye Closed: The Empiricist Agenda in Social Work Research. British Journal of Social Work 1984. 14, 1-10. Available on line: Pitts, J. 2000. Committee on the Rights of the Child: State Violence Against Children. http://www.crin.org/docs/resources/treaties/crc.25/pitts.pdf [Accessed October 2009]. Noble, C. 2004. Postmodern Thinking: Where is it Taking Social Work? Journal of Social Work. 2004. 4, 289-304. Nash, K. 2000. Readings in Contempory Political Sociology. Blackwell Publishers Ltd: Oxford. Available on line: The British Association of Social Workers has a Code of Ethics http://www.basw.co.uk/Default.aspx?tabid=64 [Accessed October 2009]. Available on line: The Scottish Social Services Codes of Practice 2005 http://www.sssc.uk.com/NR/rdonlyres/3A6C6F84-EB11-4DE2-90FF-5E143610C2B7/0/SSSCCodesofPracticebookletSept09.pdf [Accessed October 2009]. Tovey, W. 2007. The Post-Qualifying Handbook for Social Workers. Jessica Kingsley Publishers: London. Wilks, T. 2005. Social Work and Narrative Ethics. British Journal of Social Work 2005. 35, 1249-1264. Case Study In this assignment the author had to take into consideration any ethical and value based factors before exploring a workable therapeutic intervention that would meet the needs of the client within this case study. The ethical and value based dilemmas that require consideration needed to be put into a logical workable framework. The author then can identify and progressively translate to meet the needs of any ethical issues faced by both practitioner and client. This process needs to be addressed ethically in three different ways; these are the interests, rights and power. The author will then reflect, explain, analysis and use evidence on how to approach and meet the ethical needs of the client. The client will be given a pseudonym to protect and ensure confidentiality and privacy throughout this assignment, consent was also given by the main carers. The boy who will be referred to as Marc is now 12 years of age and has recently been diagnosed with (Attention Deficit Hyperactivity Disorder) ADHD which is now being challenged (Appendix 1). First and foremost, it is vitally important to look at the young person as a whole by using the Getting it Right for Every Child 2006 (GIRFEC 2006) My world Framework approach which is â€Å"underpinned by common values and principles along with shared models, tools and practices that are designed to support work with children and young people† (on line). Although GIRFEC 2006 -Proposal for Action: Analysis of Consultation Responses argue â€Å"is there sufficient emphasis and guidance about the childs involvement and are there sections which need strengthening to ensure that the child or young person is at the heart of the process?† (on line). This statement reinforces the authors need to assess all aspects of the clients wellbeing. This in turn ensures that the author considers all areas of ethical value based concerns before committing to a solution based framework to employ to the service users current situation. By utilising Collingwoods (2005) three-stage theory fr amework provided the author with a workable framework to apply a process that would then develop a flexible and developmental tool, which can then identify any specific ethical and value based issues to inform the authors intervention strategy. Consideration for background information to work ethically with client By using a Proportionism approach and by looking at the applied science model to solve any ethical issues, then by applying an existing body of professional knowledge to make sense of complex and difficult human situations. This generates an understanding of the current situation, develops a structured sequence to practice in a systematic way, then to practice in a thoughtful and professional manner to allow consideration of cultural circumstance of the current ethical dilemmas (Howe 2002). By completing the Collingwood (2005) theory circle, stage two informed the author of the theory to inform/ intervene ethically and stage three helped identify the knowledge, skills and values to work ethically with the client. The author drew on more than one principle based ethical approach. This maximised the wellbeing and minimised harm whilst following core values, principles and codes. Although applying the deontological approach allows the author the ability to create logic and ensures that the author is following ethical codes and principles as there are moral judgments and difficult ethical decisions to be made. Gray (2009) reinforces that practitioners should not undermine the importance of principles and codes. It seems logical to utilise modern workable theory to practice by employing the proportionals approach to explore present situation, consequences and sense of perception on the basis of evidence before the practitioner, using the best means available for forming judgments that springs directly from these means and allows for the end to justify the means (Gray 2009). By applying the Proportionism approach allows the author to build on, manufacture or complement theories, by transcending exi sting theories to provide a new and superior form of working ethically it can only enhance practitioner/ client relationships (Lovat and Gray 2008). The following areas were highlighted as in need of development to address the ethical issues for the client. The author believes that there is an insecure attachment base. Bowlby cited in Butterworth and Harris (1994) argues that insecure attachments contribute to the formation of a neurotic personality as they take the child down a psychologically unhealthy pathway. Developmental stage using Ericsons psychosocial stages where the child should be in the fourth stage of industry versus inferiority, recognising that it is important that the child does not run the risk of developing a sense of inferiority a sense of inadequacy resulting in feeling worthless at this stage (Slee 2002). Leading on to the general effect of the grief, after the mind has suffered an acute paroxysm of grief, and the cause still continues, we fall into a state of low spirits or feel utterly cast down and dejected (on line) (Darwin1872). Intervention It has been long recognised that practitioners have been torn between the utilitarian and the deontologists approach to social work and by breaking free and proceeding on the basis inclusion, open communication, empathy and being impartial is the way forward for practitioners (Houston 2003). â€Å"A valid moral decision is reached when those affected by it endorse it as the preferred way forward. In reaching this agreement participants must accept the consequences of the decision for all concerned and its impact on everyones interests† (Houston 2003 pg: 822). Therapeutic interventions are used in many different situations and the end goals of intervention programs are to inspire people to make the necessary changes to take control of their own lives again (on line) (When are Therapeutic Interventions Recommended?). Consideration for the clients diagnosis as being ADHD is a significant contributing factor to ensuring the best therapeutic model is used to address underlying issues. Controlled longitudinal studies show that by late adolescence and early adulthood, children identified as having ADHD are at risk for a number of mental health problems the most noticeable are anti-social behaviours, cognitive difficulties, poor academic achievement and lower occupational status (on line) ( Thorley 1998). Although diagnose of the clients ADHD is in dispute, ethically the author is at duty to include the probability of ADHD until a conclusive assessment is carried out to confirm or dismiss the first diagnosis when considering play therapy interventions. The British Association of Play Therapists (BAPT) is the foremost professional body that registers Play Therapists and regulates Play Therapy practice in Britain and have codes of practice along with play therapy standards to regulate play therapy and training (on line)(BAPT 2009). â€Å"Play Therapists need to be motivated, concerned and directed towards good ethical practice. They are required to take responsibility to maintain these standards and Play Therapists should always accept responsibility for their professional behavior and actions† (on line) (BAPT 2009). Consideration for Biesteks casework principles, individualisation, purposeful expression of feelings, controlled emotional involvement, acceptance, non-judgemental attitude, service user self-determination and confidentiality were the early foundations of principles that have paved the way for influencing present date values in social work (Banks 2006). The author drew on Biesteks casework principles but found that although Biestek theory focuses on concern of the welfare of the individual it fails to offer satisfactory accounts for relationships. The author has identified that there is a strain on positive relationships, and feels that this is an area that requires prompt development. â€Å"Ethical responsibilities flow from all human relationships, from the personal and familial to the social and professional. Ethical decision making is a process† (Webb 2003 pg: 22). Holland (2009) acknowledges that a key element within ethic of justice is that of individual rights and that this is a very important development for looked after children. The client has be informed and made aware of all aspects of the intervention process before any structured work can take place as the vast amount of therapeutic play therapy relies heavily on parent participation. This alone poses an ethical dilemma as the client is within a residential group setting and relationships between client /staff may be inconsistent. In conclusion to this assignment the author feels that it would benefit all parties if the play therapy was delayed until the new adoptive parents were approved. This would then enrich the relationships between client/ adoptive parents, furthermore they can subsequently build resilience in the new family unit, along with educating the new adoptive parents of the complex history and the future needs of the client. The long term value base and ethical benefits would outweigh any short term quick fix solution; the new adoptive parents require the best tools available to ensure that the new family unit works. References Banks, S. 3rd Ed, 2006. Ethics and Values in Social Work. Palgrave Macmillan: Basingstoke. Butterworth, G., Harris, M. 1994. Principles of Developmental Psychology. Lawrence Erlbaum Associates Ltd: UK. Collingwood, P. 2005. Integrated Theory and Practice: The Three Stage Theory Framework. The Journal of Practice Teaching in Health and Social Work, Volume 6, Number 1, 2005, pp. 6-23(18). Available on line: Darwin, R, C. 1872. The Expression of the Emotions in Man and Animals http://darwin-online.org.uk/content/frameset?itemID=F1142viewtype=textpageseq=1 [ Accessed October 2009]. Available on line: Dr. Thorley, G. 1998. Therapeutic Intervention for Attention Deficit Hyperactivity Disorder http://www.drgeoffthorley.com/ADHD%20article%201998.pdf [Accessed October 2009]. Gray, M. 2009. Moral Sources and Emergent Ethical Theories in Social Work. British Journal of Social Work, September 22, 2009.1-18. Holland, S. Looked After Children and the Ethic of Care. British Journal of Social Work. August 10 2009. 1-17. Houston, S. 2003. Establishing Virtue in Social Work: A Response to McBeth and Webb. British Journal of Social Work (2003) 33, 819-824. Lovat, T., Gray, M. 2008. Towards a Proportionist Social Work Ethics: A Habermasian Perspective. British Journal of Social Work (2008). 38, 1100-1114. Slee, T. P. 2002. 2nd Ed. Child, Adolescent, and Family Development. Cambridge University Press: UK. Available on line: The British Association of Play Therapists http://www.bapt.info/playtherapystandards.htm [Accessed October 2009]. Available on line: When are Therapeutic Interventions Recommended? http://ezinearticles.com/?When-is-Therapeutic-Interventions-Recommended?id=1499263 [Accessed October 2009]. Webb, B, N. 2003. 2nd Ed. Social Work with Children. The Guilford Press: New York. Appendix 1 Accommodated under Sec 25 C(S)Act 95 Marc was born in England. Marcs birth parents were substance users and had a chaotic lifestyle. He was unable to remain permanently in their care and as a result was fostered in a number of placements returning to the care of his parents for short periods and having sporadic contact with them. Marc blames himself for not being able to remain in their care. He was adopted by a couple in Scotland at the age of 5 years. The couple were not able to have their own children. The couple then went on to have a son of their own and since then he has been treated differently. There are no photos of Marc in the house, he does not have a bike (the brother does), he is the family scapegoat and blamed for problems in the parents relationship. Marc has since been diagnosed with ADHD and his diet restricted as a means of attempting to control this. There is some debate by health professionals as to whether the diagnosis is accurate, he is on low dose medication and there has been some reported improvement in his attention levels. Marc also has a developmental delay in self care i.e. knowing how to wash himself, toileting skills. Marc remained with his adoptive parents until last month when his parents asked for him to be removed due to their perception of his behaviour being unacceptable. Marc had stolen sweets. As a result of this Marc has been accom modated in residential home on a temporary basis until a long term family can be identified. Marc believes that stealing the sweets caused the breakdown in the relationship with his adoptive family consequently blaming himself. Recently a family has been identified and the residential unit is planning to undertake a therapeutic intervention in order to prepare Marc to have an understanding of his history and build his self esteem. The prospective adoptive family are in the process of being approved by the fostering and adoption panel.

Shakespeares Hamlet - Observations of Madness Essay -- Madness and I

Hamlet: Observations of Madness One of the most analyzed plays in existence is the tragedy Hamlet, with its recurring question: "Is Hamlet’s 'antic disposition' feigned or real?" In truth, this question can only be answered by observing the thoughts of the main characters in relation to the cause of Hamlet real or feigned madness. In the tragedy Hamlet, each of the main characters explains Hamlets madness in their own unique way. To discover the cause behind the madness of Hamlet, each character used their own ambitions, emotions and interpretations of past events. Characters tried to explain Hamlet's "antic disposition" by means of association to thwarted ambition, heartbreaking anguish, and denied love. In the workings of their thoughts, the characters inadvertently reveal something about their own desires, emotions and experiences to the reader. The thoughts of Guildenstern and Rosencrantz present the reader with one possible factor for the cause of Hamlets supposed madness. The two men believe that the cause for Hamlets madness is his lack of â€Å"advancement† or thwarted ambition. In a conversation with Hamlet in Act II scene II, Guildenstern and Rosencrantz come upon this idea: Hamlet: Denmark's a prison. Rosencrantz: Then is the world one. Hamlet: A goodly one; in which there are many confines, wards and dungeons, Denmark being one o' the worst. Rosencrantz: We think not so, my lord. Hamlet: Why, then, 'tis none to you; for there is nothing either good or bad, but thinking makes it so: to me it is a prison. When the heir apparent calls his heritage a prison, something must be seriously wrong, and it is not difficult for th... ...rman N. Holland, Sidney Homan and Bernard J. Paris. Berkeley and Los Angeles: University of California Press, 175-190. Leverenz, David. 1980. 'The Woman in Hamlet: An Interpersonal View.' In Representing Shakespeare: New Psychoanalytic Essays, edited by Coppelia Kahn and Murray M. Schwarz. Baltimore and London: The Johns Hopkins Press, 110-128. Levin, Richard. 1990. 'The Poetics and Politics of Bardicide.' PMLA 105: 491-504. Vickers, Brian. 1993. Appropriating Shakespeare: Contemporary Critical Quarrels. New Haven and London: Yale University Press. Watson, Robert N. 1990. 'Giving up the Ghost in a World of Decay: Hamlet, Revenge and Denial.' Renaissance Drama 21:199-223. Wright, George T. 1981. 'Hendiadys and Hamlet.' PMLA 96:168-193. Shakespeare, William. The Tradegy of Hamlet Prince of Denmark. New York: Washington Square Press, 1992

The Push Mower From Hell :: Personal Narrative, Autobiographical Essay

The Push Mower From Hell "It's time to get up, son. You've got work to do today." My father's gravelly voice brought my reluctant subconscious out of the realm of its peaceful slumber. How dare he, I wondered to myself, interrupt my rest and force me awake on the most sacred of days: the Cartoon Sabbath. Still slightly disoriented, I went into the kitchen to feed myself a bowl of Cheerios and plant myself in front of a "Winnie the Pooh" rerun. I had scarcely finished my third bowl when my father returned, somewhat angered. "I believe that I told you that we were going to do some yardwork today. How about coming out and lending a hand?" I agreed meekly, owing to the fact that I had no desire to risk conflict with my father. After brushing my teeth and slapping on a tee shirt, shorts, and shoes, I trudged outside. The hot summer sun beat down heavily on the back of my neck. Because of a combination of heat and fatigue, I felt as if I were drunk. I staggered over to the riding lawnmower, relieved by the thought of being able to sit down while appeasing my parents at the same time. My brother, the impish little troll that he is, having the same idea, had already confiscated the mower for his own selfish gain. He had left for the lot next door, which was easy to cut compared to the banks that I was left with. I gave him an evil glance that shouted my disapproval of his actions and marched towards the much hated, seldom used push mower. The push mower was an angry, rust ridden, hostile beast of ill intent. I don't think anyone in my family ever expected to have to use the beast, so it became more like a family joke to see whom we could stick it to each time grass needed to be cut. It was temperamental and took at least five minutes of heavy pulling on the unforgiving cord to finally get it started. It had at one time been a self propelled mower, but the chain broke long ago, leaving a free spinning gear rotating dangerously near the operator's low appendages. The machine gave off a low threatening growl, reminding us to approach it with a certain amount of animosity, if not respect.

A Report on the Link Between Management Principles, Functions and Organisation Structure

A REPORT ON THE LINK BETWEEN MANAGEMENT PRINCIPLES, FUNCTIONS AND ORGANISATION STRUCTURE ESHUL RAYHAN ID 103718-86 TABLE OF CONTENTS PAGE NO. SUMMARY†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 3 INTRODUCTION†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦ 4 FUNCTION OF PLANNING LINKING WITH MANAGEMENT PRINCIPLES AND ORGANIZATIONAL STRUCTURE†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 5 FUNCTION OF ORGANISING LINKING WITH MANAGEMENT PRINCIPLES AND ORGANIZATIONAL STRUCTUREâ₠¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 7 FUNCTION OF LEADING WITH MANAGEMENT PRINCIPLES ANDORGANIZATIONAL STRUCTURE†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 8 FUNCTION OF CONTROLLING WITH MANAGEMENT PRINCIPLES AND ORGANIZATIONAL STRUCTURE†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 9 CONCLUSION†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦. 10 REFERENCE LIST†¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢ € ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦Ã¢â‚¬ ¦11 SUMMARY The report shows the connection between the four functions of management, Planning, Organizing, Leading and Controlling with the Management Principles and Organizational Structures are designed to imply the factors for the successful operation of a business organization like Marks and Spencer.Examples has been drawn to support the ideas and put light on the scenarios in the organization. INTRODUCTION The motto of the following report is to identify and highlight the connection between the management principles, functions and organizational structure. Every organization has the application of these three factors as better outcomes are achieved when they are linked together and implied. The management principles affect the management functions which have a great influence on the organizational str ucture.This report is using ‘MARKS AND SPENCER’ as an example to show how the three affect on each other. Management is the process of getting activities completed efficiently and effectively through other people. It includes various processes and steps which will be further discussed in the following report. There are 14 management principles as stated by Henry Fayol ( Boddy, 2005 ). Many of them are linked with the functions of management which are, Planning, Organizing, Controlling and Leading.The report is to show the relations between the three factors of the business and how are they implied. FUNCTION OF PLANNING LINKING WITH MANAGEMENT PRINCIPLES AND ORGANISATIONAL STRUCTURE Planning is an essential component of management function to carry out the smooth operation of a business. It contains the property of identifying the obejectives of a business by the management team. When the plans are being made, the changes are implied immediately or according to a time sp an as required according to the current status of the business.For a successful planning, forecasting is very necessary for the management as it helps them to be prepared for the worst case scenarios and to earn more revenues as well. This very function management can be linked with one of the management principles as stated by a French business analyst named Henry Fayol, which is Unity of Direction. The author defines the principle as the combination of group of people who work together to achieve the same organizational goals and performs the activities in a definite synchronized system to achieve them with maximum efficiency.For example, if we look into a press release by Marks and Spencer during their AGM in 11th July 2011, it is seen that the Chairman and CEO of the company, Mr. Luc Vandevelde announced that the company is going to bring a significant change in their planning and thus a change in their organizational structure as well. He also announced the new planning strateg ies which will be carried out to maximize profits for the company. The plans were implied from 29th March 2001. It included the selling of their own brands only but not any other external brands anymore.This is done to reattain the fame regarding the quality of own products as customers experienced no extra facilities buying external brands from Marks and Spencer and neither the external brand companies nor Marks and Spencer could gain any outstanding revenue selling exrternal brand products. To make this come into action, the company decided to return to their own suppliers who had been supplying the very own products dedicated for the selling purpose of Marks and Spencer only. This would result to the attainment of the former business relations and strong future commitments and the uphill formation of M & S business achievements.The second plan was to close down the subsidiary companies which were making losses rather than profits M & S. For example, Brooks Brothers and Kings Supe r Market in USA were sold off as they were loss-making companies and were affecting the gross profit margin of M & S. The company also decided to close down the stores in Central Europe as it was not making profits. These plans were made and implied after research being made by the superiors of the company and the structures had been re-organized.This is where the organizational structure comes into action when the company sort out and design the strategies to overcome the difficulties and perform smooth business actions. FUNCTION OF ORGANISING LINKING WITH MANAGEMENT PRINCIPLE AND ORGANIZATIONAL STRUCTURE Organizing is the process of combining human, physical and financial resources to achieve organizational goals. It is important to carefully dedicate the resources to maximize profits since resources are always limited. This is synchronized with the ‘Division of Labor’ management principle by Henry Fayol.This factor of management principle is described by the author t hat the every duty of an organization is spread evenly among the employees to ease out the process of output. If we draw an example regarding M & S, its seen that the duties are segregated between the employees. The organization is structured from the Chairman to Customer Service Assistant, where, they have different tasks to complete. This results to finish and achieve goals within less time and with more efficiency as there is a saying that,’ A load of ten is a burden of one’.Each of the employee are asked to perform their own definite task which then becomes a positive outcome when made total. FUNCTION OF LEADING LINKING WITH MANAGEMENT PRINCIPLES AND ORGANIZATIONAL STRUCTURE Management needs to exercise the function of leading in order for the organization to achieve their goals. It is an essential part of the management as it helps the management to direct employees to focus on ‘the big picture’. Normally management focuses on increasing productivity to improve cost efficiency. To improve productivity employees need direction and motivation.The direction and motivation are usually received from superiors. This can be linked with the management principle of ‘Authority and Responsibility’ which means to have the power to order the sub-ordinates and direct them to achieving goals. For example, M & S have the supervisors who lead the Retail Operatives to fulfill the targets which are set by the Managers to the supervisors. It follows a chain of command which has the ultimate goal of maximizing profit. The chain of command starts from the highest level of authority like the Chairman and ends to the Retail Operatives’ tasks.FUNCTION OF CONTROLLING LINKING WITH MANAGEMENT PRINCIPLES AND ORGANIZATIONAL STRUCTURE Management must use the function of Control to maximize employee performance and stabilize the working environment. There had been always a controversy where it is widely believed that Controlling is a negati ve term because the employees regard it to be a restriction. But at the very conclusion, it helps to maintain a strict guideline which the employees must follow to avoid chaos. â€Å"Managers expect people in an organization to change their behavior in response to control† (Erven, 1994).This can be inter related with management principle of â€Å"Discipline†, which is clearly stated by Fayol that there should be certain rules which are to be followed must by the employees. When it is looked into M & S, it is apparent that the company applies a number of rules which must be obliged by the employees to create a better working environment and prevent any internal hassles within the company. Therefore, the organization has been structured in such format where certain rules are set in purpose to keep the working environment healthy and prosperous in respect to business aspects. CONCLUSIONFrom the report it is apparent that Management Functions are greatly influenced by the Management Principles based on which the organization is being structured. The achievement of organizational goals are highly affected due to the implication of these three management factors. It is fair to conclude that, for an organization to make profit and carry out its operation in long run, the application of these management factors are inevitable. REFERENCE LIST 1. Boddy, D (2005), Management Concepts and Principles, Prentice Hall 2. [Online] http://corporate. marksandspencer. com/aboutus/ourhistory, Accessed at 12/04/2011

Physics Study Notes Hsc

Physics Summary Contents Core Topic One: Space 1. 2. 3. 4. Gravity Space Launch and Return Future Space Travel Special Relativity 2 3 13 14 Page Core Topic Two: Motors and Generators 1. 2. 3. 4. 5. The Motor Effect Electromagnetic Induction Electric Generators Transformers Electric Motors 19 24 27 29 31 Core Topic Three: From Ideas to Implementation 1. 2. 3. 4. Cathode Rays Quantum Theory Solid State Devices Superconductivity 32 37 43 48 Option Topic: Quanta to Quarks 1. . 3. 4. 5. 6. Models of the Atom Quantum Physics The Electron Microscope Applications of Radioactivity Nuclear Applications The Structure of Matter 53 57 59 61 66 67 William Kim HSC Physics Summary | page 1 Core Topic One: Space 1. The Earth has a gravitational field that exerts a force on objects both on it and around it  § Define weight as the force on an object due to a gravitational field The weight of an object is the force of gravity acting on it. r W = mg Where W is the weight in newtons (N), m is the mass i n kilograms (kg) and g can be either: 1. The acceleration due to gravity (= 9. 8 m/s/s at the Earth’s surface); or 2. The gravitational field strength (= 9. 8 N/kg at the Earth’s surface).  § Define gravitational potential energy as the work done to move an object from a very large distance away to a point in a gravitational field. As we lift an object from the ground to a height above the ground we do work on it. This work is stored in the object as gravitational potential energy.For an object of mass m at a height h above the Earth’s surface the gravitational potential energy E is given by: E p = mgh However this equation is valid only when the object is near the Earth’s surface. The gravitational potential energy is a measure of the work done in moving an object from infinity to a point in the field. The general expression for the gravitational potential energy of an object of mass m at a distance r from the centre of the Earth (or other planet) is g iven by: E p = ? G mM E r Newton’s Law of Universal Gravitation m F = G 12 2 r where G is the universal gravitational constant. The Gravitational Field Surrounding any object with mass is a gravitational field. g= Gm r2 Where M is the mass of the Earth (or other planet). Change in Gravitational Potential Energy The change in potential energy of a mass m1 as it moves from infinity to a distance r from a source of a gravitational field (due to a mass m2) is given by: mm ? E p = G 1 2 r Change in Gravitational Potential Energy Near the Earth (when radius increases from A to B) ?1 1? ?E p = GmM E ? ? ? ?r ? ? A rB ? William Kim HSC Physics Summary | page 2 . Many factors have to be taken into account to achieve a successful rocket launch, maintain a stable orbit and return to Earth  § Describe the trajectory of an object undergoing projectile motion within the Earth’s gravitational field in terms of horizontal and vertical components Any moving object that moves only und er the force of gravity is a projectile. The horizontal motion of a projectile is independent to the vertical motion. The reason for this result is that gravity is the only force acting on the objects and this always acts towards the centre of the Earth.Projectile motion can be analysed by realising that: 1. The horizontal motion is constant velocity. 2. The vertical motion of constant acceleration (with acceleration of g). Equations of Uniformly Accelerated Motion r r r v = u + at r r 1r s = ut + at 2 2 2 2 v = u + 2 as The Path of a Projectile The velocity at any point of the path of a projectile is simply the vector sum of the horizontal and vertical velocity components at that point. ?y = k (? x ) 2 ? ag ? k =? 2 ? ? 2u ? ? x? The horizontal component is constant.The vertical component changes at g, the acceleration due to gravity. Trajectories The path followed by a projectile – its trajectory – is a parabola (or linear) (1) Horizontal motion: ? x = u x t 1 (2) Ve rtical motion: ? y = a g t 2 2 From (1): ? x t= ux Combining (2) & (3): 1 ? ?x ? 1 ag ? y = a g ? ? = (? x )2 2 ? u ? 2 ? x? 2 ux 2 ux ? y ? x William Kim HSC Physics Summary | page 3  § Describe Galileo’s analysis of projectile motion Galileo was responsible for deducing the parabolic shape of the trajectory of a projectile.Galileo’s analysis of projectile motion led him to consider reference frames. These are what all measurements are compared to. The concept of Galilean relativity refers that the laws of mechanics are the same in a frame of reference that is at rest or one that moves with constant velocity.  § Explain the concept of escape velocity in terms of the: o gravitational constant o mass and radius of the planet If an object is projected upward with a large enough velocity it can escape the gravitational pull of the Earth (or other planet) and go into space.The necessary velocity to leave the Earth (or other planet) is called the escape velocity. Escape velocity depends on the gravitational constant, the mass and radius of the planet. Suppose an object of mass m is projected vertically upward from the Earth’s surface (mass of M and radius R) with an initial velocity u. The initial mechanical energy, that is, kinetic and potential energy is given by: E k i + E pi = 1 M m mu 2 ? G E 2 RE Let us assume that the initial speed is just enough so that the object reaches infinity with zero velocity.The value of the initial velocity for which this occurs is the escape velocity ve . When the object is at infinity the mechanical energy is zero (the kinetic energy is zero since the velocity is zero and the potential energy is zero because this is where we selected the zero of potential energy). Hence 1 M m mve2 ? G E = 0 which leads to: 2 RE ve = 2GM E RE William Kim HSC Physics Summary | page 4  § Discuss Newton’s analysis of escape velocity Circular Motion The motion of an object in a circular path with constant speed is cal led uniform circular motion.Although the speed remains the same in uniform circular motion, it follows that an object travelling in a circular path must be accelerating, since the velocity (that is, the speed in a given direction) is continually changing. r r v1 ? v2 v1 = v 2 r v2 r The change in velocity is given by: v2 r r r r v1 ? v = v 2 ? v1 r ? v1 r r ? v r and since: a = ? v r ? t ? v it follows that the object is accelerating. Isaac Newton proposed the idea of artificial satellites of the Earth. He considered how a projectile could be launched horizontally from the top of a high mountain so that it would not fall to Earth.As the launch velocity was increased, the distance that the object would travel before hitting the Earth would increase until such a time that the velocity would be sufficient to put the object into orbit around the Earth. (A higher velocity would lead to the object escaping from the Earth. ) Centripetal Acceleration As can be seen, when the change in veloc ity is placed in the average position between v1 and v2, it is directed towards the centre of the circle. When an object is moving with uniform circular motion, the acceleration (the centripetal acceleration) is directed towards the centre of the circle.For an object moving in a circle of radius r with an orbital velocity of v, the centripetal acceleration a is given by: v2 ac = r Earth Orbits A satellite can be put into Earth orbit by lifting it to a sufficient height and then giving it the required horizontal velocity so that it does not fall back to Earth. For the satellite to circle the Earth, the centripetal force required is provided by the gravitational attraction between the satellite and the Earth. Hence the centripetal acceleration is given by: v2 g= R William Kim HSC Physics Summary | page 5  §Use the term ‘g forces’ to explain the forces acting on an astronaut during launch g-forces on Astronauts Humans can withstand 4g without undue concern. Accelerations up to ~10g are tolerable for short times when the acceleration is directed parallel to a line drawn between the person’s front and back. The human body is relatively unaffected by high speeds. Changes in speed, however, that is, accelerations, can and do affect the human body creating ‘acceleration stress’. g-forces Acceleration forces – g-forces – are measured in units of gravitational acceleration g.For example, a force of 5g is equivalent to acceleration five times the acceleration due to gravity. If the accelerations are along the body’s long axis then two distinct effects are possible: 1. If the acceleration is in the direction of the person’s head they may experience a ‘black out’ as the blood rushes to their feet; or 2. If the acceleration is towards their feet, they may experience a ‘red out’ where the blood rushes to their head and retina.  § Compare the forces acting on an astronaut during launch with what happens during a roller coaster rideAs you ‘fall’ from a height, you experience negative g-forces (you feel lighter). When you ‘pull out’ of a dip after a hill or follow an ‘inside loop’, you experience positive g-forces (you feel heavier). The positive g-forces are like those astronauts experience at lift-off. Consider a rider in a car at the bottom of an inside loop. The rider has two forces acting on them: 1. Their normal weight (mg) acting down; and 2. The ‘normal reaction force’ (N) acting up. This is the push of the seat upwards on their bottom.Assume that the loop is part of a circle of radius R. A centripetal force is required for the rider to travel in a circle. This is the difference between the normal force and the weight force, that is: mv 2 mv 2 N ? mg = : N = mg + R R The g-forces are found from the ‘normal force’ divided by the weight. That is: N = mg mg + mv 2 2 R = 1+ v mg gR N mg g’s felt by rider = William Kim HSC Physics Summary | page 6  § Discuss the impact of the Earth’s orbital motion and its rotational motion on the launch of a rocketA moving platform offers a boost to the velocity of a projectile launched from it, if launched in the direction of motion of the platform. This principle is used in the launch of a rocket by considering that the Earth revolves around the Sun at 107,000km/h relative to the Sun and rotates once on its axis per day so that a point on the Equator has a rotational velocity of approximately 1,700km/h relative to the Sun. Hence, the Earth is itself a moving platform with two different motions which can be exploited in a rocket launch to gain a boost in velocity.Earth Orbit A rocket heading into orbit is launched to the east to receive a velocity boost from the Earth’s rotational motion. An Interplanetary Trip The flight of a rocket heading into space is timed so that it can head out in the direction of the Earth†™s motion and thereby receive an extra boost.  § Analyse the changing acceleration of a rocket during launch in terms of the: Law of Conservation of Momentum Forces experienced by astronauts Law of Conservation of Momentum Rocket engines generate thrust by burning fuel and expelling the resulting gases.Conservation of momentum means that as the gases move one way, the rocket moves the other. (Momentum before the burning is zero; hence the momentum after is also zero. The gases carry momentum in one direction down, and so the rocket carries an equal momentum in the opposite direction up. ) As fuel is consumed and the gases expelled, the mass of the system decreases. Since acceleration is proportional to the thrust and inversely proportional to the mass, as the mass decreases, the acceleration increases. Hence the forces on the astronauts increase.Forces Experienced by Astronauts g forces varied during the launch of Saturn V, a large three-stage rocket used to launch the Apollo sp acecraft. This is attributed to the sequential shutdown of the multiple rocket engines of each stage – a technique designed specifically to avoid extreme g forces. William Kim HSC Physics Summary | page 7  § Analyse the forces involved in uniform circular motion for a range of objects, including satellites orbiting the Earth Motion Whirling rock on a string Electron orbiting atomic nucleus Car cornering Moon revolving around Earth Satellite revolving around EarthFc Provided By†¦ The string Electron-nucleus electrical attraction Friction between tyres and road Moon-Earth gravitational attraction Satellite-Earth gravitational attraction  § Compare qualitatively and quantitatively low Earth and geostationary orbits Low Earth Orbit A low Earth orbit is generally an orbit higher than approximately 250 km, in order to avoid atmospheric drag, and lower than approximately 1000 km, which is the altitude at which the Van Allen radiation belts start to appear.The space shuttle utilises a low Earth orbit somewhere between 250 km and 400 km depending upon the mission. At 250 km, an orbiting spacecraft has a velocity of 27,900km/h and takes just 90 minutes to complete an orbit of the Earth. Geostationary Orbit A geostationary orbit is at an altitude at which the period of the orbit precisely matches that of the Earth. If over the Equator, such an orbit would allow a satellite to remain ‘parked’ over a fixed point on the surface of the Earth throughout the day and night.From the Earth such a satellite appears to be stationary in the sky, always located in the same direction regardless of the time of day. This is particularly useful for communications satellites because a receiving dish need only point to a fixed spot In the sky in order to remain in contact with the satellite. The altitude of such an orbit is approximately 38,800 km. If a satellite at this height is not positioned over the Equator but at some other latitude, it will not remain fi xed at one point in the sky.Instead, from the Earth the satellite will appear to trace out a ‘figure of eight’ path each 24 hours. It still has a period equal to the Earth’s, however, and so this orbit is referred to as geosynchronous. William Kim HSC Physics Summary | page 8  § Discuss the important of Newton’s Law of Universal Gravitation in understanding and calculating the motion of satellites Using Newton’s Law of Universal Gravitation combined with the expression for centripetal force, we can see that the orbital velocity required for a particular orbit depends nly on the mass of the Earth, the radius of the Earth and the altitude of the orbit (distance from the surface of the Earth). Given that the mass and radius of the Earth have fixed values, this means that altitude is the only variable that determines the specific velocity required. In addition, the greater the radius of the orbit, the lower the orbital velocity required. Once a launch ed rocket has achieved a sufficient altitude above the surface of the Earth, it can be accelerated into an orbit. It must attain a specific speed that is dependent only upon the mass and radius of the Earth and the altitude above it.If that speed is not reached, the spacecraft will spiral back in until it re-enters the atmosphere; if the speed is exceeded, it will spiral out. This can be considered by appreciating that the simplest orbital motion is a uniform speed along a circular path around the Earth. Uniform circular motion, as already mentioned, is a circular motion with a uniform orbital velocity. According to Newton’s First Law of Motion, a spacecraft in orbit around the Earth, or any object in circular motion, requires some force to keep it there, otherwise it would fly off at a tangent to the circle.This force is directed back towards the centre of the circle. In the case of spacecraft, it is the gravitational attraction between the Earth and the spacecraft that acts to maintain the circular motion that is the orbit. The force required to maintain circular motion, known as centripetal force, can be determined using the following equation: mv 2 FC = r The application of Newton’s Law of Universal Gravitation to the orbital motion of a satellite will produce an expression for the critical orbital velocity mentioned earlier.Recall that this law states that the gravitational attraction between a satellite and the Earth would be given by the following expression: m m FG = G E 2 S r This gravitational force of attraction also serves as the centripetal force for the circular orbital motion, hence: FG = FC Therefore, we can equate the formula for FG with that for FC: m E mS m S v 2 G = r r2 ? v = GmE r where v = orbital velocity (ms-1) where r = rE + altitude (m) William Kim HSC Physics Summary | page 9 Kepler’s Third Law: The Law of Periods Further, we can use the expression for orbital velocity to prove Kepler’s Third Law – the Law of Periods.The period or the time taken to complete one full orbit can be found by dividing the length of the orbit (the circumference of the circle) by the orbital velocity, v. 2? r T= v Changing the subject of this expression to v and then substituting into the formula for v given above: 2? r Gm E = T r 3 Gm E r ? 2 = T 4? 2 This means that for any satellite of the Earth at any altitude, the ratio r3:T2 always equals the same fixed value. William Kim HSC Physics Summary | page 10  § Describe how a slingshot effect is provided by planets for space probesMany of today’s space probes to distant planets such as Jupiter use a gravitational ‘slingshot’ effect (also known as a gravity-assist trajectory) that brings the probe close to other planets to increase the probe’s velocity. In 1974, Mariner 10 was directed past Venus on its way to Mercury. The Pioneer and Voyager probes also used this method. Consider a trip to Jupiter such as the Galileo prob e that involved a single fly-by of Venus and two of the Earth. As the probe approaches Venus, it is accelerated by Venus’ gravitational attraction, causing it to speed up relative to Venus. By Newton’s Third Law, Venus will also experience a force slowing it down. It’s mass, however, is so much greater than that of the probe that the velocity decrease is imperceptible. ) As the probe passes Venus, its speed is reduced (relative to Venus). Relative to the Sun, however, its speed has increased. The probe picks up angular momentum from the planet (which loses an equal amount of an angular momentum). Gravity allows the ‘coupling’ between the probe and planet to facilitate the transfer. For this reason, gravity-assist trajectories should more correctly be called angular momentum-assist trajectories. f = vi + 2Vi Planet vi Spacecraft Vi Vf  § Account for the orbital decay of satellites in low Earth orbit All satellites in low Earth orbit are subject to some degree of atmospheric drag that will eventually decay their orbit and limit their lifetimes. As a satellite slows, it loses altitude and begins a slow spiral downwards. As it descends, it encounters higher density air and higher drag, speeding up the process. By the time the satellite is below an altitude of 200 km it has only a few hours left before colliding with the Earth. The re-entry process generates much heat and most satellites burn up (vaporise) before impacting.William Kim HSC Physics Summary | page 11  § Discuss issues associated with safe re-entry into the Earth’s atmosphere and landing on the Earth’s surface There are significant technical difficulties involved in safe re-entry, the most important being: 1. The heat generated as the spacecraft contacts the Earth’s atmosphere; and 2. Keeping the retarding-forces (g-forces) within safe limits for humans. Heating Effects The Earth’s atmosphere provides aerodynamic drag on the spacecraft a nd as a result high temperatures are generated by friction with air molecules. Identify that there is an optimum angle for re-entry into the Earth’s atmosphere and the consequences of failing to achieve this angle. g-Forces The angle of re-entry is critical: too shallow and the spacecraft will bounce off the atmosphere back into space; too steep and the g-forces will be too great for the crew to survive (and the temperatures generated with the atmosphere will be too high even for the refracting materials used). The ‘allowed’ angle of re-entry is –6. 2 °  ± 1 ° relative to the Earth’s horizon. William Kim HSC Physics Summary | page 12 3.Future space travel and exploration will entail a combination of new technologies based on current and emerging knowledge  § Discuss the limitation of current maximum velocities being too slow for extended space travel to be viable Scientists have not yet been able to produce speeds of spacecraft more than a f ew tens of thousands of kilometres per hour. When travelling to distant planetary objects, the engines of spacecraft are not on as spacecraft rely on inertia to move along. To increase the speed significantly would require the engines to be operating, which would require more fuel.More fuel would require more thrust putting the spacecraft into orbit, which would require more fuel and so on. To increase the speed of spacecraft to values that would make interplanetary travel feasible requires a whole new technology (one not based on the emission of gases produced by combustion). Clearly, while current maximum velocities are just adequate for interplanetary travel, they are entirely inadequate for interstellar travel.  § Describe difficulties associated with effective and reliable communications between satellites and earth caused by: – distance – van Allen radiation belts – sunspot activityDistance Microwaves and radio waves, like all EM waves, travel through sp ace at the speed of light. This is the fastest speed possible in our universe and therefore places a limit on the speed and response time of space communications. The immense distance involved in space communications creates a distance-related time lag. Also, as EM radiation obeys an inverse square law, there is a loss of signal strength as distance increases. This is referred to as space loss. Van Allen radiation belts There are two belts of energetic charged particles, mainly electrons and protons, lying at right angles to the equator of the Earth.Some of the solar wind particles become trapped in the Van Allen radiation belts. Intense solar activity can disrupt the Van Allen Belts. This in turn is associated with auroras and magnetic storms. The charged particles drifting around the Earth in the outer belt corresponds to an electric current and hence has an associated magnetic field. Once or twice a month this current increases and as a result its magnetic field increases. This c an lead to interference of short wave radio communication, errors in communication satellites and even failure of electrical transmission lines.Sunspot activity Sunspots are associated with the solar wind (consisting of a stream of charged particles). The solar wind affects the Earth’s magnetic field and this in turn affects radio communication. William Kim HSC Physics Summary | page 13 4. Current and emerging understanding about time and space has been dependent upon earlier models of the transmission of light  § Outline the features of the ether model for the transmission of light It was believed that light waves require a medium to propagate. Although nobody could find such a medium, belief in its existence was so strong that it was given a name – the ether.The ether: – Filled all of space, had low density and was perfectly transparent – Permeated all matter and yet was completely permeable to material objects – Had great elasticity to support and propagate the light waves  § Describe and evaluate the Michelson-Morley attempt to measure the relative velocity of the Earth through the ether The Ether Wind Because the Earth was moving around the Sun, it was reasoned that an ether wind should be blowing past the Earth. However, if a wind blows, the speed of sound relative to the stationary observer would vary.Thus it was believed that the speed of light should vary due to the presence of the â€Å"ether wind†. It was in an attempt to detect this difference that Michelson and Morley did their famous experiment. The Michelson-Morley Experiment Light sent from S is split into two perpendicular beams by the half-silvered mirror at A. These two beams are then reflected back by the mirrors M1 and M2 and are recombined in the observer’s eye. An interference pattern results from these two beams. The beam AM1 travelled across the ether, whilst AM2 travelled with and against the ether.The times to do this can be shown to be different and so introduce a phase difference between the beams. When the entire apparatus was rotated through 90 °, a change in the interference pattern was expected. None was observed. The result of the Michelson-Morley experiment was that no motion of the Earth relative to the ether was detectable. M1 A S M2 Ether Wind  § Discuss the role of critical experiments in science, such as Michelson-Morley’s, in making determinations about competing theories From a hypothesis, predictions are made of what should happen if a particular experiment is performed.If the results are not in agreement with the prediction, the hypothesis is incorrect. As we have seen, the fact that a null result was found from this experiment showed the ether hypothesis to be invalid. This opened up a completely revolutionary view of space and time with the work of Einstein. William Kim HSC Physics Summary | page 14  § Outline the nature of inertial frames of reference Frames of Reference Frame s of reference are objects or coordinate systems with respect to which we take measurements. Position In maths, the Cartesian coordinate system is used and position is referred to the axes x, y and z.In experiments in class, the laboratory is the frame of reference. S S' r u r P v Velocity An object P travels with velocity v with respect to a reference frame S. Another frame S’ moves with velocity u relative to S. The velocity of P relative to S’ is v’ = v – u. Velocity thus depends upon the reference frame. Inertial Frames of Reference An inertial frame of reference is one that is moving with constant velocity or is at rest (the two conditions being indistinguishable). In such reference frames, Newton’s Law of Inertia holds. A non-inertial frame of reference is one that is accelerating.  § Discuss the principle of relativityThree hundred years before Einstein, Galileo posed a simple idea, now called the principle of relativity, which states that all steady motion is relative and cannot be detected without reference to an outside point. This idea can be found built into Newton’s First Law of Motion as well. Two points to be reinforced:  § The principle of relativity applies only for non-accelerated steady motion  § This principle states that within an inertial frame of reference you cannot perform any mechanical experiment or observation that would reveal to you whether you were moving with uniform velocity or standing still.William Kim HSC Physics Summary | page 15  § Identify the significance of Einstein’s assumption of the constancy of the speed of light In 1905, Albert Einstein proposed that the speed of light is constant and is independent of the speed of the source or the observer. This premise explained the ‘negative’ result of the MichelsonMorley experiment and showed that the ether concept was not needed. As a consequence of this ‘law of light’ it can be shown that ther e is no such thing as an absolute frame of reference. All inertial reference frames are equivalent. That is, all motion is relative.The laws of physics are the same in all frames of reference; that is, the principle of relativity always holds.  § Recognise that if c is constant then space and time become relative In Newtonian physics, distance and velocity can be relative terms, but time is an absolute and fundamental quantity. Einstein radically altered the assumptions of Newtonian physics so that now the speed of light is absolute, and space and time are both relative quantities that depend upon the motion of the observer. (Our reality is what we measure it to be. Reality and observation cannot be separated. Remember this as we proceed).  §Discuss the concept that length standards are defined in terms of time with reference to the original meter †¦In other words, the measured length of an object and the time taken by an event depend entirely upon the velocity of the obser ver. (This is why our current standard of length is defined in terms of time – the metre is the distance travelled by light in a vacuum in the fraction 1/299792458 of a second).  § Identify the usefulness of discussing space/time, rather than simple space †¦Further to this, since neither space nor time is absolute, the theory of relativity has replaced them with the concept of a space-time continuum. Space and time, not just space, are relative quantities).  § Account for the need, when considering space/time, to define events using four dimensions †¦Any event then has four dimensions (three space coordinates plus a time coordinate) that fully define its position within its frame of reference. William Kim HSC Physics Summary | page 16  § Explain qualitatively and quantitatively the consequence of special relativity in relation to: The relativity of simultaneity The equivalence between mass and energy Length contraction Time dilationThe Relativity of Simultanei ty (simultaneity and the velocity of light) Observers in relative motion will disagree on the simultaneity of events separated in space. The Equivalence Between Mass and Energy The mass of a ‘moving’ object is greater than when it is ‘stationary’ – it experiences mass dilation (covered later). Since c is the maximum speed in the universe it follows that a steady force applied to an object cannot continue to accelerate. It follows that the inertia, that is the resistance to acceleration, must increase.But inertia is a measure of mass and so the mass has increased. It is this increase in mass that prevents any object from exceeding the speed of light, because as it accelerates to higher velocities its mass increases, which means that further accelerations will require even greater force. This is further complicated by time dilation because, as speeds increase to near light speed, any applied force has less and less time in which to act. The combined ef fect is that as mass becomes infinite and time dilates, an infinite force would be required to achieve any acceleration at all.Sufficient force can never be supplied to accelerate beyond the speed of light. If force is applied to an object, then work is done on it – energy is given to the object. This energy would take the form of increased kinetic energy as the object speeds up. But at near light speed the object does not speed up. The applied force is giving energy to the object and the object does not acquire the kinetic energy we would expect. Instead, it acquires extra mass. Einstein made an inference here and stated that the mass (or inertia) of the object contained the extra energy.Relativity results in a new definition of energy as follows: E = E k + mc 2 where E = total energy, Ek = kinetic energy, m = mass, c = speed of light When an object is stationary, it has no kinetic energy, but still has some energy due to its mass. This is called its mass energy or rest ener gy and is given by: 8 -1 E = mc 2 where E = rest energy (J), m = mass (kg), c = speed of light (3 x 10 m s ) William Kim HSC Physics Summary | page 17 Implications of Special Relativity: To measure speed we need to measure distance and time. If c remains constant, then it follows that distance (length) and time must change.Space and time are relative concepts. Length Contraction (the Lorentz-FitzGerald Contraction) The length of a ‘moving’ rod appears to contract in the direction of motion relative to a ‘stationary’ observer. l = l0 1 ? v2 c2 where l is the moving length, l0 is the ‘rest’ length (that is, the length as measured by an observer at rest with respect to the rod) and v is the speed of the rod. Time Dilation Time in a ‘moving’ frame appears to go slower relative to a ‘stationary’ observer t= t0 1? v c2 2 where t is the observed time for a ‘stationary’ observer and t0 is the time for an observer travelling in the frame. 0 is called the proper time (this is the time measured by an observer present at the same location as the events that indicate the start and end of an event). Mass Dilation The mass of a ‘moving’ object is greater than when it is ‘stationary’. m= m0 1? v2 c2 where m is the mass for a ‘moving’ object and m0 is the mass for that object when it is ‘stationary. ’  § Discuss the implications of time dilation and length contraction for space travel The relativity of time allows for space travel into the future but not into the past.When travelling at relativistic speeds (0. 1c or faster), relativity influences the time that passes on the spacecraft. Astronauts on a relativistic interstellar journey would find their trip has taken fewer years than observed on Earth. William Kim HSC Physics Summary | page 18 Core Topic Two: Motors and Generators 1. Motors use the effect of forces on current-carrying conductors in magnetic fields  § Identify that moving charged particles in a magnetic field experience a force Charged particles moving in an external magnetic field will experience a force.If the moving charged particles are flowing through, and confined within, a conductor that is in an external magnetic field, the conductor will also experience a force. This effect is known as the motor effect. F = qvB Use left hand â€Å"FBI gun† An example: Van Allen Radiation Belts The Earth’s magnetic field captures charged particles from the solar wind (low energy) and cosmic rays (high energy). The charges are force to spiral along the field lines accumulating into two doughnut-shaped belts of â€Å"radiation† called the upper and lower Van Allen radiation belts.William Kim HSC Physics Summary | page 19  § Discuss the effect, on the magnitude of the force on a current-carrying conductor, of variations in: The strength of the magnetic field in which it is located The magnitude of the current in the conductor The length of the conductor in the external magnetic field The angle between the direction of the external magnetic field and the direction of the length of the conductor †¦The force is proportional to the magnetic field strength, B †¦The force is proportional to the current, I †¦The force is proportional to the length, L The force is at a maximum when the conductor is at right angles to the field, and is zero when the conductor is parallel to the field. The magnitude of the force is proportional to the component of the field that is at right angles to the conductor. F = BIl sin ? William Kim HSC Physics Summary | page 20  § Describe qualitatively and quantitatively the force on long parallel current-carrying conductors: Ampere’s Law Two parallel wires, each carrying a current, will exert a force on the other. This happens because each current produces a magnetic field (as in Oersted’s experiment).Therefore each wire finds itself carrying a current across the magnetic field produced by the other wire and hence experiences a force. Determining the magnitude of the force between two parallel conductors The magnetic field strength at a distance, d, from a long straight conductor carrying a current, I, can be found using the formula: kI B= d -7 -2 where k = 2. 0 x 10 N A The magnitude of the force experienced by a length, l, of a conductor due to to an external magnetic field is: F = I 2 lB or ? kI ? F = I 2l ? 1 ? ? d ? rearranged F II =k 1 2 l d F II =k 1 2 l d (Ampere’s law) I1 I2 If currents are in the same direction, then the conductors will attract. If currents are in opposite directions, then the conductors will repel. William Kim HSC Physics Summary | page 21  § Define torque as the turning moment of a force using: Torque is turning force. Its’ units are Newton-metres (Nm). ? = Fd where ? = torque, in Nm F = force, in N D = distance from rotational axis, in m F = BIl ? =BIld Rotat ional axis d ? = Fd  § Identify the forces experienced by a currentcarrying loop in a magnetic field and describe the net result of the forces b max ? = nBIA zero ? b Current Loops N I F = BIl ? =BIld ? = ? 1 + ? 2 = BIld + BIld = 2 BIld = BI (l ? 2d ) = BIA S ? = nBIA cos ? ? b (For each turn of the loop) Generally, ? =nBIA cos ? William Kim HSC Physics Summary | page 22  § Account for the motor effect due to the force acting on a current-carrying conductor in a magnetic field The motor effect Recall that charged particles moving in an external magnetic field will experience a force. If the moving charged particles are flowing through, and confined within, a conductor that is in an external magnetic field, the conductor will also experience a force.An electric motor is a device that transforms electrical potential energy into rotational kinetic energy.  § Describe the main features of a DC electric motor  § Discuss the importance of the invention of the commutator for devel oping electric motors  § Describe the role of the metal split ring and the brushes in the operation of the commutator Anatomy of a DC motor – Permanent magnets: provide an external magnetic field in which the coil rotates. As the magnets are fixed, they are known as the stator. – Rotating coil: carries a direct current that interacts with the magnetic field, producing torque. Armature: is made of ferromagnetic material and allows the coil to rotate freely on an axle. The armature and coil together are known as the rotor. The armature protrudes from the motor casing, enabling the movement of the coil to be used to do work. – Commutators: reverse the current of the coil every half turn to maintain consistent direction and torque. It is a mechanical switch that automatically changes the direction of the current flowing through the coil when the torque falls to zero. – Brushes: maintain electrical contact of coils with the rest of the circuit.The developmen t of DC motors outstripped that of AC motors and generators for two reasons: – Voltaic batteries could supply power – They could use powerful electromagnets that were far stronger than permanent magnets The development of the commutator was important because it led to the development of modern electric motors and generators. It enabled motors to provide steady circular motion of a drive shaft.  § Describe how the required magnetic fields can be produced either by currentcarrying coils or permanent magnets The magnetic field of a DC motor can be provided either by permanent magnets or by electromagnets.William Kim HSC Physics Summary | page 23 2. The relative motion between a conductor and magnetic field is used to generate an electrical voltage  § Outline Michael Faraday’s discovery of the generation of an electric current by a moving magnet Faraday had found that 3 things are necessary to generate (or â€Å"induce†) an EMF (voltage supply): – A magnetic field (from some magnets or electromagnet) – A conductor (eg. wire or coil of wire) – Relative motion / change between the field and the conductor If the conductor formed a closed loop then an induced current would also flow. ire If this wire is dropped so that it cuts flux lines, then a voltage appears between the ends because electrons are forced to the right. They eventually stop moving because they create an electric field pushing them back. As long as the magnet is moving, an emf and current is induced. Faraday’s Law ? =? n ? where ? = induced EMF, in V n = number of turns on coil ? = change in ? = magnetic flux, in Wb = BA B = magnetic flux density (field strength), in T The induced voltage can be increased by: Increasing n: more turns on the coil Increasing B: use strong magnets Increasing A: use a bigger coil Decreasing t: go faster! B A = area of coil in m 2 ? = time taken for to occur William Kim HSC Physics Summary | page 24  § Define ma gnetic field strength B as magnetic flux density Magnetic flux density is the magnetic flux per unit area and is a measure of the magnetic field strength.  § Explain the concept of magnetic flux in terms of magnetic flux density and surface area ? = BA sin ? where B = magnetic flux density, in T A = area, in m 2 ? = magnetic flux, in Wb  § Explain generated potential difference as the rate of change of magnetic flux through a circuit The induced emf is proportional to the rate of change of flux through the circuit.See Faraday’s Law (above).  § Account for Lenz’s Law in terms of conservation of energy and relate it to the production of back emf in motors Lenz’s Law This is a supplementary law to Faraday’s Law. It says that any induced emf or current will have a direction that opposes the change that caused it. This is really just a restatement of the law of conservation of energy because the induced electrical energy has come from the thing that caus es the original motion. Eg. In a hydroelectric power station, the kinetic energy of flowing water is converted into electrical energy. NWilliam Kim HSC Physics Summary | page 25  § Explain that, in electric motors, back emf opposes the supply emf Back emf Back emf is generated in any coil that experiences changing B fields, even though it is producing them. Note that back emf is frequency dependent – the higher the frequency of the changing field, the greater the back emf produced. Back emf is also produced in the rotating coil of a motor: – When the motor is spinning at its operating speed, back emf will have its max value, but†¦ – When the motor is just turned on it isn’t spinning yet so there is no back emf. This can lead to excessive current so the motor may be protected by using a â€Å"starting resistance† that limits current. When up to speed the resistor is taken out of the circuit. The coil becomes an electromagnet and generates an alternating B field BUT it also experiences the changing B field and generates its own emf that opposes the applied emf.  § Apply Lenz’s Law to the production of eddy currents Eddy Currents – are induced currents (usually unwanted or unintended) in two-dimensional conductors (eg. sheet metal) or three-dimensional conductors (eg. a block of steel).Sometimes it is necessary to design against them. Eg. the core of a motor is made of soft iron, and is made of thin layers (laminated) to prevent eddy currents. Some devices rely on eddy currents to work: Electromagnetic braking – a moving conductor near magnets will slow down because the eddy currents oppose its motion. Electromagnetic switching – security ‘gates’ that are really coils with AC generate a high frequency B field. Metal in this field develops eddy currents that work against the field, slowing it down. A detector circuit picks up on this and sets off an alarm.Induction Cooktops- are a n application of Faraday’s Law. Instead of a heating element, this cooktop contains a set of coils with alternating current passing through them. This produces a changing B field above the cooktop. A metal saucepan placed on the cooktop is a conductor in the changing B field and therefore an electric current is induced in the base of the pan. The current heats the pan, and this heat cooks the food. Induction cooktops are approximately twice as efficient as a gas cooktop, but are expensive to purchase. William Kim HSC Physics Summary | page 26 ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? Movement of metal Eddy current loop 3. Generators are used to provide large scale power production in isolated areas and as a backup in emergency situations  § Identify the main components of a generator An electric generator (dynamo) is a device that includes all of the elements necessary to transform mechanical kinetic energy to electricity according to Faraday’s Law: – A magnetic field (provided by a set of permanent magnets); – A conductor (a coil mounted on an axle, so it can spin); – Relative motion (the coil is made to spin by some other form of energy). Compare the structure and function of a generator to an electric motor In fact, most generators are constructed just like a motor, however the flow of energy through them is different. Motor: electrical energy a kinetic energy Generator: kinetic energy a electrical energy  § Describe the operation of an AC and a DC generator EMF is generated in the coil and a circuit is completed to the outside world through ring connectors, just like motors. If standard slip rings are used then a dynamo naturally produces alternating current AC. I t E t Doubling the frequency of rotation doubles the maximum induced emf If a split ring commutator is used instead, then the direction of the current flowing from the coil is reversed every ? cycle. This produces a pu lsing type of direct current DC. + I t William Kim HSC Physics Summary | page 27  § Discuss the energy losses that occur as energy is fed through transmission lines from the generator to the consumer Analyse the effects of the development of AC and DC generators on society and the environmentEven good electrical conductors like copper used to supply electricity, sometimes through considerable cable lengths to towns and cities, generate substantial resistances. It follows that to minimise energy loss in the wires, the current needs to be kept low (heating losses vary as the square of the current). This is achieved by transmitting the energy at high voltages.  § Impact on society – Impact on environment – Positive Improved lifestyle Street lighting Electric trains Communication Computerisation of many systems eg. anking, stock market Industrial development a more jobs Lots of electric trains have reduced pollution from steam trains and made public transport more avai lable Electricity has replaced older, more-polluting technologies eg. electrical heating instead of coal burning in fireplaces – Negative Possible risk of cancer living near distribution cables Longer working hours Reliance on electricity leaves us vulnerable to systems loss due to electrical failure – – –Burning coal in power stations produces smoke and CO2 (a greenhouse gas) Nuclear power stations produce radioactive water & have a risk of nuclear accident Hydroelectric schemes redirect water away from river habitats Mining impacts negatively on environment Visual pollution of cables  § Assess evidence about the physiological effects on humans living near high voltage power lines 1979 study found children living near high voltage power lines appeared to develop a particular form of cancer. 997 study showed no evidence of an increase risk of childhood cancer at residential magnetic field levels. 1998 panel stated that EM fields should be considered â⠂¬Å"possible human carcinogens† and that there is â€Å"no conclusive and consistent evidence that EM fields cause any human disease. † William Kim HSC Physics Summary | page 28 4. Transformers allow generated voltage to be either increased or decreased before it is used  § Explain the purpose and principles of transformers in electrical circuits A transformer is a device that alters the voltage and current of an electricity supply.The AC voltage source produces an alternating current in the primary coil. This produces an alternating B field that threads through the secondary coil. The secondary coil now has: – Conductor – B field – Change and therefore generates its own voltage. If there is a closed loop then an alternating current will flow as well.  § Compare step-up and stepdown transformers Step-up transformers: increase voltage and decrease current Step-down transformers: decrease voltage and increase current  §Determine the relationship between the ratio of the number of turns in the primary and secondary coils and the ratio of primary to secondary voltage Vp = primary voltage (voltage in) Ip = primary current np = number of turns on primary coil Vs = secondary voltage (voltage out) Is = secondary current ns = number of turns on secondary coil Vp Vs = np ns If 100% efficient (this needs perfect â€Å"flux linkage†, usually using an iron core) then: Power in primary = Power in secondary ? V p I p = Vs I s ? ? Vp Vs Vp Vs = = Is Ip np ns = Is IpWilliam Kim HSC Physics Summary | page 29  § Explain why voltage transformations are related to the conservation of energy The Principle of Conservation of Energy states that energy cannot be created or destroyed but that it can be transformed from one form to another. This means that if a step-up transformer gives a greater voltage at the output, its current must be decreased: i. e. power in = power out.  § Explain the role of transformers in electricity sub-stati ons NSW power stations produce electricity with a voltage of about 23,000 V and a current of about 30,000 A.Unfortunately, this amount is too high to be sent through a cable. This is because it heats the cable causing energy loss. This is called joule heating and happens because: P = I2R So to reduce joule heating, the current must be reduced as much as possible with a step-up transformer. Additional transformers between the power station and consumer (in sub-stations) gradually stepdown the voltage, to 240 V by the time it gets to household users. This is because at high voltages, electricity can conduct through air, making it dangerous for use in the home. Discuss why some electrical appliances in the home that are connected to the mains domestic power supply use a transformer Most electronic circuits are designed to operate at low DC voltages of between 3 V and 12 V. Therefore, household appliances that have electronic circuits in them will have either a plug-in transformer or an inbuilt transformer to step down the domestic 240 V supply. These transformers also have a rectifier circuit built into them that converts AC to DC.TVs also contain a step-up transformer for producing the high voltages needed for the CRT.  § Analyse the impact of the development of transformers on society The development of the generator and transformer has allowed for the setting up of national power grids in almost every country, making that most convenient and flexible form of energy, electricity, accessible from many miles away. The transformer’s role is to step voltage up and down to make efficient transportation and distribution possible. William Kim HSC Physics Summary | page 30 5.Motors are used in industries and the home usually to convert electrical energy into more useful forms of energy  § Describe the main features of an AC electric motor AC induction motor: – The rotor – end rings short circuit non-ferrous rotor bars, that is sealed i. e. no e xternal connections at all (usually a â€Å"squirrel cage†). Encased in a laminated iron armature. – The stator – surrounding electromagnet. – Connection to stator – the surrounding electromagnet receives the AC. In an AC induction motor, the principle of operation is: 1. AC to surrounding electromagnet, which†¦ 2.Produces an oscillating (rotating) B field, which†¦ 3. Induces a current in the rotor, which†¦ 4. Turns the rotor into an electromagnet that†¦ 5. Tries to oppose the field being generated by the stator. 6. The stator and the rotor push against each other (using their B fields), which†¦ 7. Causes the rotor to turn! Brilliant! AC (synchronous) motor: – A rotating coil – Surrounding magnets – Connection to coil via slip rings (commutator for DC motor)  § Explain that AC motors usually produce low power and relate this to their use in power tools Power is the rate of work. Work is done when ener gy is transformed from one type to another.Induction motors are considered to produce low power because the amount of mechanical work they achieve is low compared with the electrical energy consumed. The ‘lost power’ of induction motors is consumed in magnetising the working parts of the motor and in creating induction currents in the rotor. AC induction motors are considered to be unsuitable for use in heavy industry because their low power rating would make them too expensive to run when performing a specific task. However, they are used extensively in power tools and electric domestic appliances where the loss of power is not economically significant. Explain the advantages of induction motors Advantages of AC induction motors: 1. Simplicity of design; 2. High efficiency (hence low maintenance – there are no brushes or commutators to wear out); 3. Relatively low cost William Kim HSC Physics Summary | page 31 Core Topic Three: From Ideas to Implementation 1. In creased understandings of cathode rays led to the development of television  § Explain that cathode ray tubes allowed the manipulation of a stream of charged particles Discharge Tubes – Investigation of vacuum tubes could not occur until good vacuum pumps had been invented.A vacuum tube is a glass tube fitted with an electrode at either end, and almost all of the air sucked out. – The positive electrode is the â€Å"anode†; The negative electrode is the â€Å"cathode†. When a high voltage is connected between the electrodes, an invisible ray travels from the cathode to the anode. They were called â€Å"cathode rays†. Cathode rays cause glass to glow green. – A discharge tube is a cathode ray tube with a vacuum pump fitted, so that the air pressure inside the tube can be varied. At different air pressures, different bright effects appear in the tubes e. . bands, striations and dark spaces. These are caused by cathode rays striking atoms in the air inside the tube. The atoms become excited then release photons of visible light – A beam of electrons travels from the cathode to the anode and can be deflected by electrical and/or magnetic fields. Anode Glass glows here Cathode  § Explain why the apparent inconsistent behaviour of cathode rays caused debate as to whether they were charged particles or electromagnetic waves In 1892 Hertz demonstrated that cathode rays could penetrate thin metal foils.This he believed supported a wave nature. In 1895 Jean-Baptise Perrin showed that cathode rays deposited negative charges on impact with an object, suggesting a particle nature. There was controversy over the nature of cathode rays – waves or particles. William Kim HSC Physics Summary | page 32  § Identify that charged plates produce an electric field If metal plates are separated by a distance and are attached to a power source, an electric field will be produced between them. E = V/d  § Describe quantitati vely the force acting on a charge moving through a magnetic fieldRecall that the force (F) acting on a charge (q) moving with a velocity (v) at an angle to a magnetic field (B), is given by: FB = qvB Where FB = magnetic force (N) q = charge (C) v = velocity of charge (ms-1) B = magnetic field strength (T)  § Discuss qualitatively the electric field strength due to a point charge, positive and negative charges and oppositely charged parallel plates. Describe quantitatively the electric field due to oppositely charged parallel plates ++++++++ If a positive charge is placed near another positive charge, it will experience a force of repulsion.A positive charge placed in a field will experience a force in the direction of the arrow. A negative charge placed in a field will experience a force opposite to the direction of the arrow.  § FE = qE Where FE = electric force (N) q = charge (C) E = electric field strength (NC-1) ———– William Kim HSC Physics Summar y | page 33  § Outline Thomson’s experiment to measure the charge/mass ratio of an electron Cathode ray particles ? v? B ? ? ? ? ? ? ? FM ? ? FE ? ? ? v? E ? ? ? J. J. Thomson’s Experiment – By fitting plates to his CRT, he could subject the cathode rays to an electric field.The rays deflected, proving that they were charged particles, not electromagnetic waves. – He noticed that the rays deflected toward the positive plate, proving that they were negatively charged particles. – By crossing electric and magnetic fields, Thomson was able to deduce the velocity of the cathode rays. By turning off the E field, the particles followed a circular arc caused by the B field. The magnetic force was acting like a centripetal force. mv qvB = r q v ? = m Br – 2 ? FM = FE qvB = qE E ? v = B Thomson adjusted the strength of the fields so that the particles were not deflected.By carefully measuring the strength of the fields, Thomson could calculate v. T homson had already measured B and worked out v. By measuring the radius of curvature r, he could then calculate q/m, i. e. the charge/mass ratio of an electron. q/m for these particles was 1800 times greater than for a hydrogen ion, the simplest known atomic ion. Thomson quickly compared the charges and found them to be about the same (though opposite in sign) Therefore mass for cathode ray particles was 1800 times smaller than hydrogen Therefore cathode ray particles were subatomic particles!This was the first discovery of subatomic particles They were later called electrons. William Kim HSC Physics Summary | page 34  § Outline the role in a cathode ray tube of: Electrodes in the electrode gun The electric field The fluorescent screen The Cathode Ray Tube Each CRT has a vacuum tube/chamber, a cathode, an anode, and a target. Electrodes in the electron gun The electron gun produces a narrow beam of electrons. It consists of a filament, a cathode and two open-cylinder anodes. The a nodes help to accelerate and focus the electrons.A ring shaped electrode – the grid – between the cathode and anodes controls the brightness of the spot by controlling the number of electrons emitted by the gun. By making the grid negative with respect to the cathode the number of electrons, and hence the brightness is reduced. The electric field Acts as a deflection system. It consists of two sets of parallel plates connected to a parallel plates connected to a potential difference. This produces an electric field between the plates. The Y-plates control the vertical deflection and the X-plates the horizontal deflection.The fluorescent screen The inside glass of the end of the tube is coated with a fluorescent material for example, zinc sulphide. When an electron beam hits the screen, the coating fluoresces and a spot of light is seen on the screen. The screen acts as a detector of cathode rays. Electrons Cathode Anode To plates and screen William Kim HSC Physics Summ ary | page 35  § Outline applications of cathode rays in oscilloscopes, electron microscopes and television sets The Cathode Ray Oscilloscope (CRO) Is an electronics diagnostics device because it can show a graph of how voltages vary over time.Deflection of the electron beam is achieved by two sets of plates. Horizontal plates cause vertical deflection while vertical plates cause horizontal deflection. TV Tube An electron gun again produces the electron beam. Coils are used instead of plates, however. Electric current through the coils produce magnetic fields that can deflect the beams quickly from side to side, and more slowly from bottom to top. In this way the beam scans the entire screen. By varying the intensity of the beam, a picture is built up. The picture is refreshed 50 times / second, which is too fast to be noticed by the human eye.The Electron Microscope Uses electrons instead of light. Their wavelength is 100,000 times smaller than visible light, therefore their reso lving power is 100,000 times greater. – A â€Å"sample† is placed inside the chamber (which is really the CRT) – The air is then sucked out – An electron gun produces the electron beam – Coils produce magnetic fields to focus the beam (â€Å"magnetic lenses†) – The beam scans over the surface of the sample – Detectors pick up the reflected and scattered electron beam, and from this information a 3 dimensional image is constructed  §Discuss the impact of increased understandings of cathode rays and the development of the oscilloscope on experimental physics The introduction of electronic control systems into all forms of science and industry has seen the cathode ray oscilloscope (CRO) become one of the most widely utilised test instruments. Because of its ability to make ‘voltages’ visible, the cathode ray oscilloscope is a powerful diagnostic and development tool. William Kim HSC Physics Summary | page 36 2.The r econceptualisation of the model of light led to an understanding of the photoelectric effect and black body radiation  § Explain qualitatively Hertz’s experiments in measuring the speed of radio waves and how they relate to light waves Recall: Maxwell’s theory of electromagnetic waves In 1864 Maxwell, through a set of four brilliant equations, predicted a range of invisible waves made up of an electric and magnetic wave that regenerate each other. The speed of these waves was calculated to be 3 x 108 ms-1 and probably included light.E v B Heinrich Hertz’s Experiment: (proving Maxwell’s theory) Performed in 1886, Hertz built equipment to generate and transmit EM waves with ? ? 1m. He also had a separate receiver (a loop of wire) located about 20m away. Spark gaps were included to show when high voltage AC was present in the transmitter or receiver. The receiver spark only appeared when the transmitter spark was present. Hertz hypothesised that the sparks set up changing electric and magnetic fields that propagated as an electromagnetic ave, as postulated by Maxwell. He showed that these were waves being transmitted because he could reflect, refract and polarise them. By measuring the frequency, he calculated v (v = f ? ) and it came out as 3 x 108 ms-1. These properties proved Maxwell’s theory and as they are also exhibited by light, Hertz was able to provide experimental evidence that light is a form of transverse electromagnetic wave. to induction coil < 1mm gap transmitter charged plates receiver William Kim HSC Physics Summary | page 37  §Describe Hertz’s observation of the effect of a radio wave on a receiver and the photoelectric effect he produced but failed to investigate Outline applications of the production of electromagnetic waves by oscillating electric charges in radio antennae Hertz observed that the transmitter spark was producing s