Investigation of resistivity of nichrome wire Essay Example for Free

Investigation of resistivity of nichrome wire Essay 32 Gauge 28 Gauge Voltage Recorded Percentage Uncertainty % Ammeter The ammeter recorded the current of the circuit with the wire connected to it. 32 Gauge 28 Gauge Current Recorded Percentage Uncertainty %( Current Recorded Percentage Uncertainty. Resistance Thus, as the resistance is calculated using the voltage and current obtained, we have the following resistance percentage uncertainties. 32 Gauge Resistance Uncertainty %( Gauge Resistance Uncertainty % Resistivity This is calculated using the resistance, area and the length. The uncertainties of the resistance and length are used to calculate the uncertainty of the resistivity. The area was not used as it was found by using the gauge value and checked against a referenced site, where diameters were published. As this value was given, the uncertainty was not counted as the method of measurement was not stated. 32 Gauge 28 Gauge Resistivity Uncertainty %(Discussion As the investigation took place, the voltage was increased slowly. This increased the current passing through the circuit. From these values obtained for each of the wires, the resistance and resistivity were calculated. The resistance was calculated from both the values obtained from the experiments and also from the gradient of the graph drawn. This was done so that separate set of resistivities can be obtained and evaluated. As seen from the calculations of the resistance, it is proportional to the length of the wire. The longer the nichrome wire is, the larger the resistance will be. This was certainly the case here as the resistance for the 1 metre wire was more than double that of the 0. 5 metre wire. This larger resistance would be due to the cross-sectional area of the wires. Were the 1 metre wire had a cross-sectional area of 5. 9 x 10-8 m2, the 0. 5 metre was 1. 1 x 10-7 m2, therefore the first nichrome being longer and thinner, causes the resistance to be much larger. The resistivity was calculated for each of the nichrome wires and was found to be very close to one another. The slight difference could be due to experimental errors. The 32gauge wire had a much larger resistance, while being the longer wire and had the thinner cross-sectional area. Taking this all into consideration, the resistivity was calculated at varying voltages and the mean value was 1. 0149 x 10-6 ? m. The gradient from the graph is the resistance, this again was used to calculate a separate value of the resistivity, which was 1. 01496 x 10-6 ? m. This was done as the trend line of the graph was set to the intercept of zero, as when there is no power through the circuit there would be no voltage or current. This value is the same as the value found from the obtained tabulated results. The calculated resistivities for the 28gauge gave similar values. Here the mean value from the obtained current and voltage was 1. 095 x 10-6 ? m, where as the resistivity calculated from the gradient of the graph was 1. 12 x 10-6 ? m. Although these values looking different they are of the standard form of negative 6, meaning they are very small numbers, and therefore this slight difference is minute. Again this resistivity for the 28 gauge in comparison to the resistivity for the 32 gauge is the same, where very small decimal places are slightly out. This investigation led to determining a good value for the resistivity by using two wires of different dimensions. The accepted value for the resistivity of nichrome is 1. 50 i 10-6 ? m. This in ratio to the values obtained is as follows: 32 Gauge 1 This shows that the values obtained are very close to that of the accepted value. To improve the accuracy of the results the experiment should be repeated. In doing so, some variables should be kept constant i. e. the length, gauge or temperature so that an average can be obtained. Bibliography http://www. 8886. co. uk/ref/standard_wire_gauge. htm http://hyperphysics. phy-astr. gsu. edu/hbase/electric/resis. html http://en. wikipedia. org/wiki/Electrical_resistivity Physics Assignment 3 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Electricity and Magnetism section.

Excellence in Education :: essays research papers

The concept of excellence in education is one that, on the surface, seems to be unquestionable. After all, who would not accede that students within our schools should, in fact, excel? Certainly teachers, parents, and administrators can agree on excellence as an aim to shoot for. The interpretation of the term "excellence" is, however, less obvious. How do we regard excellence? Is it the college bound student with a broad liberal arts education? Is it the student who graduates high school trained in a specific trade? Many in the field of education cannot come to an agreement on how our schools can best achieve excellence for and from our students. One of the many authorities who have contributed a model for what schools should be is Robert L. Ebel. According to Ebel, knowledge is the single most significant and most important goal in the education of children. In his article "What are schools for?" Ebel answers "that schools are for learning, and that what ought to be learned mostly is useful knowledge" (3). He builds this declaration in answer to trends in education that focus upon other aspects of learning in schools. Ebel states in the beginning of his article, that he does not assume schools should be social research agencies, recreational facilities, adjustment centers, or custodial institutions. (3). While he does not deny that our nation is currently wrestling with a dreary array of social ailments, he does argue that the answer to such problems can or should lie within the jurisdiction of our schools. In discussing education’s mission to provide useful knowledge, Ebel defines what he means by the word knowledge: "It is an integrated structure of relationships among concepts and propositions" (5). Knowledge, the way Ebel describes it is not the same as information. Ebel states that "knowledge is built out of information by thinking". Knowledge, according to Ebel, must be constructed from information by each individual learner; it cannot be looked up, or given to students by a parent or teacher. " A student must earn the right to say ‘I know’ by his own thoughtful efforts to understand" (Ebel, 5). The intellectual proficiencies many educators hope to teach are, like information, essentially useless to Ebel without a knowledge base on which to draw from. Ebel feels that a good teacher can "motivate, direct, and assist the learning process to great advantage". Although Ebel feels that good teachers are essential to providing a "favorable learning environment," he puts much of the accountability for learning on the students themselves. Ebel feels that teachers are there to facilitate students in their learning, not to coerce those who are indifferent and unmotivated and do not wish to learn, against their will.

Hope Focused Marriage Counseling Essay

Unlike other explorations insinuated in the context of research, marriage counseling has been one of the unspecialized fields emerged with theoretical assumptions and practice (Stuckert, 2003). This however, has been the challenge to psychologists and practitioners in defying the thought that marriage cannot be taken into research since its hypotheses and results of practice have been acclimated, nevertheless the volume available for study is accumulated. Everett L. Worthington Jr. , a psychology professor and the proponent of over 150 articles tackling issues on marriage, forgiveness and reconciliation was able to find standard procedures on how to keep marriages anchored on Christianity based marital therapy. More specifically, through the light of his year 1999 published book, Hope-Focused Marriage Counseling, couples are to be taken to a self rehabilitation which will give hope to individuals who are living in a room full of skeptic viewpoints about marriage and eventually open a realization that his substantial research shall lead them to a path where â€Å"miracles do happen in the real world. † (Worthington, 1999) Overview Marriage is a shadow of the relationship that we are expected to have with Jesus—permanent, loving, committed. (Eph 5:32) Everett L. Worthington begins his book with a verse in the bible which depicts the meaning of marriage in the most moral and Christian way thus giving a connotation that helping troubled couples is not an easy task. However, she points out the fact that the extent of healing relationships is through developing a character of Christ embodied in every individual’s personality and manifest such with one’s relationships to his or her social network as well (Worthington, 1999). Further, he stresses that when a relationship has Christ as vanguard, life will be inhabited with the verity of love, faith and hope and that then is the start of a bright thing. Strengths What makes his book amazing falls on the grounds of analytic and realistic situations as the core of the gist of the whole scenario. Initially introducing theories then later putting the theories into practice makes readers able to divulge their selves in the dimension that the author intends them to live with. His strategies (advices, so to speak) draws out a hysteria which will make readers know their respective state in life at first, hence, for having been given the momentum to realize what is happening in their lives, they will seek for answers on how to save them from their presumed agony. Further, his approaches through exercises which are efficient to exhibit (Worthington, 1999)—drawing fundamental values, the promotion of confession and forgiveness, communication intensification, aiding conflict resolution, alterations of the pattern of thinking, intimacy development, and the cementing of commitment—gives grandeur to the book as readers can implement these exercises with their partners or core groups. Realistically crafted, he gives marriage counseling a twist by inculcating his own experiences which gives conviction to the statements and recommendations written in his book. One fascinating fact on the book is its distinctiveness in course, since unlike other books on marriage counseling, typically establishing manuals which synonymously suggest divorce or annulment so as not to complicate the situation, this book thinks otherwise. Though the author admitted that is hard and rarely possible in the contemporary society—divorce is legal and other forms of law that allow couples to â€Å"live† without the need of marital rites—still, he fervently believes that the sacred matrimony must be preserved even if others no longer accept as true the tradition and the essence of spiritual intimacy. These ideas represented in the book will coin back the integrity, accountability, prudence and proper teaching among couples. Weaknesses â€Å"Hope-focused rather than problem-focused† (Worthington, 1999) this is the toweringly hopeful campaign of the author. Thus, because of globalization, cultural diversity and the differences of every individual, there may be some who may not appreciate the book for reasons that inhibit the issue on dissimilarity of character, viewpoint in life, tradition and environmental influences. It is evident that the target audiences of the book are Christians—although optimistic individuals would also be interested in reading the book—hence this leads us to a remorseful realization that it will not drive â€Å"naysayer† or a pessimist to read it. Still, fingers are crossed on the intent of the book, and that is to spread the thought that â€Å"change is possible† and in the long run, every couple will be given a new outlook on their marriage for the benefit of their family. Conclusions and further remarks The functions of the husband and the wife bear a multifaceted blueprint of expectations of the responses which are to come from one another. Hence as humans, challenges and trials are inevitable aspects in life and must therefore be taken with full accountability after having vowed under the sacred matrimony and under the blessing of the church. However, in the present era, where several factors influence every person’s character and personality, asking for help and intervention from one who truly understands the quintessence of love and marriage is a an ideal act to do (Stuckert, 2003). Communication mostly is the main problem of couples and Worthington is able to help by producing a masterpiece which, with confidence, he believes will save troubled marriages. Forgive. Reconcile. Change can happen if one will listen while the other speaks. References Stuckert, R. P. (2003). Role Perception and Marital Satisfaction. A Configurational Approach. Marriage and Family Living, 25(4), 415-419. Worthington, E. L. (1999). Hope-Focused Marriage Counseling: A Guide to Brief Therapy. Downers Grove, IL: InterVarsity Press.

Understanding and Processing Keyboard Events in Delphi

Keyboard events, along with mouse events, are the primary elements of a users interaction with your program. Below is information on three events that let you capture a users keystrokes in a Delphi application: OnKeyDown, OnKeyUp and OnKeyPress. Down, Up, Press, Down, Up, Press... Delphi applications can use two methods for receiving the input from the keyboard. If a user has to type something in an application, the easiest way to receive that input is to use one of the controls that automatically responds to keypresses, such as Edit. At other times and for more general purposes, however, we can create procedures in a form that handle three events recognized by forms and by any component that accepts keyboard input. We can write event handlers for these events to respond to any key or key combination the user might press at runtime. Here are those events: OnKeyDown - called when any key on the keyboard is pressedOnKeyUp - called when any key on the keyboard is releasedOnKeyPress - called when a key corresponding to an ASCII character is pressed Keyboard Handlers All the keyboard events have one parameter in common. The Key parameter is the key on the keyboard and is used to pass by reference of the value of the pressed key. The Shift parameter (in the OnKeyDown and OnKeyUp procedures) indicates whether the Shift, Alt, or Ctrl keys are combined with the keystroke. The Sender parameter references the control that was used to call the method. procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState) ; ... procedure TForm1.FormKeyUp(Sender: TObject; var Key: Word; Shift: TShiftState) ; ... procedure TForm1.FormKeyPress(Sender: TObject; var Key: Char) ; Responding when the user presses shortcut or accelerator keys, such as those provided with menu commands, does not require writing event handlers. What Is Focus? Focus is the ability to receive user input through the mouse or keyboard. Only the object that has the focus can receive a keyboard event. Also, only one component per form can be active, or have the focus, in a running application at any given time. Some components, such as TImage, TPaintBox, TPanel and TLabel cannot receive focus. In general, components derived from TGraphicControl are unable to receive focus. Additionally, components that are invisible at run time (TTimer) cannot receive focus. OnKeyDown, OnKeyUp The OnKeyDown and OnKeyUp events provide the lowest level of keyboard response. Both OnKeyDown and OnKeyUp handlers can respond to all keyboard keys, including function keys and keys combined with the Shift, Alt, and Ctrl keys. The keyboard events are not mutually exclusive. When the user presses a key, both the OnKeyDown and OnKeyPress events are generated, and when the user releases the key, the  OnKeyUp event is generated. When the user presses one of the keys that OnKeyPress does not detect, only the  OnKeyDown event occurs, followed by the  OnKeyUp event. If you hold down a key, the OnKeyUp event occurs after all the OnKeyDown and OnKeyPress events have occurred. OnKeyPress OnKeyPress returns a different ASCII character for g and G, but OnKeyDown and OnKeyUp do not make a distinction between uppercase and lowercase alpha keys. Key and Shift Parameters Since the Key parameter is passed by reference, the event handler can change Key so that the application sees a different key as being involved in the event. This is a way to limit the kinds of characters that the user can input, like to prevent users from typing alpha keys. if Key in [a..z] [A..Z] then Key : #0 The above statement checks whether the Key parameter is in the union of two sets: lowercase characters (i.e. a  through z) and uppercase characters (A-Z). If so, the statement assigns the character value of zero to Key to prevent any input into the Edit component, for example, when it receives the modified key. For non-alphanumeric keys, WinAPI virtual key codes can be used to determine the key pressed. Windows defines special constants for each key the user can press. For example, VK_RIGHT is the virtual key code for the Right Arrow key. To get the key state of some special keys like TAB or PageUp, we can use the GetKeyState Windows API call. The key status specifies whether the key is up, down, or toggled (on or off - alternating each time the key is pressed). if HiWord(GetKeyState(vk_PageUp)) 0 then ShowMessage(PageUp - DOWN) else ShowMessage(PageUp - UP) ; In the OnKeyDown and OnKeyUp events, Key is an unsigned Word value that represents a Windows virtual key. In order to get the character value from Key,  we use the Chr function. In the OnKeyPress event, Key is a Char value that represents an ASCII character. Both OnKeyDown and OnKeyUp events use the Shift parameter, of type TShiftState, a set flags to determine the state of the Alt, Ctrl, and Shift keys when a key is pressed. For example, when you press Ctrl A, the following key events are generated: KeyDown (Ctrl) // ssCtrl KeyDown (CtrlA) //ssCtrl A KeyPress (A) KeyUp (CtrlA) Redirecting Keyboard Events to The Form To trap keystrokes at the form level instead of passing them to the forms components, set the forms KeyPreview property to True (using the Object Inspector). The component still sees the event, but the form has an opportunity to handle it first - to allow or disallow some keys to be pressed, for example. Suppose you have several Edit components on a form and the Form.OnKeyPress procedure looks like: procedure TForm1.FormKeyPress(Sender: TObject; var Key: Char) ; begin if Key in [0..9] then Key : #0 end; If one of the Edit components has the Focus,  and the  KeyPreview property of a form is False, this code will not execute. In other words, if the user presses the 5 key, the 5 character will appear in the focused Edit component. However, if the KeyPreview is set to True, then  the forms OnKeyPress event is executed before the Edit component sees the key that is pressed. Again, if the user has pressed the 5 key, then it assigns the character value of zero to Key to prevent numerical input into the Edit component.