Ohmmeter

Resistance Measurement ENE 240 Electrical and Electronic Measurement (2/2008) Class 8, January 14, 2009 Werapon Chiracharit, Ph. D. , ENE, KMUTT werapon. [email  protected] ac. th 1 Analogue Ohmmeter †¢ Permanent-magnet moving-coil (Galvanometer, ? ? I ) with a total resistance Rg †¢ Series type ohmmeter with battery E †¢ Resistance R to be measured †¢ Rz to be zero-ohm-adjusted Rz R E + – Rg 2 1 Zero-Ohm Adjustment †¢ Short circuit at the terminals 0? Resistance reading is zero, R = 0 †¢ Adjust Rz for a full-scale current reading E = Ifsd (Rz + Rg) Ifsd = E / (Rz + Rg) †¢ E and Rg are constant †¢ Change Rz (change Ifsd) for multirange 3 Zero-Ohm Adjustment (Cont’d) †¢ for the series type ohmmeter E = I (R + Rz + Rg) I = E / (R + Rz + Rg) †¢ R increased, I decreased, ? decreased †¢ Relationship between I and R is non-linear, it means a non-linear resistance scale. †¢ Rz and Rg are small, then for high resista nces, the scale points are very close together! 4 2 Shunt Type Ohmmeter †¢ When R = ? (open circuit), R1 is adjusted for a full-scale reading. E = Ifsd (R1 + Rg) Ifsd = E / (R1 + Rg) R1 R Ig IR Rg E 5 I Shunt Type Ohmmeter (Cont’d) †¢ When R is connected, the current passing through the meter is reduced by shunt resistor. 1/Rparallel = 1/R + 1/Rg Rparallel = RRg / (R + Rg) and E = I (R1 + Rparallel) = I (R1 + RRg/(R + Rg)) = I (R1R + R1Rg + RRg) / (R + Rg) = I (R1Rg + R(R1 + Rg)) / (R + Rg) 6 3 Shunt Type Ohmmeter (Cont’d) †¢ The current I is divided into 2 parts. IgRg = IRR Ig = I – IR = I – IgRg/R therefore Ig = E(R + Rg)/(R1Rg + R(R1 + Rg)) – IgRg/R Ig(1+Rg/R) = E(R + Rg)/(R1Rg + R(R1 + Rg)) Ig(R+Rg)/R = E(R + Rg)/(R1Rg + R(R1 + Rg)) Ig = ER / (R1Rg + R(R1 + Rg)) †¢ Meter reading depends on the value of R, though R is a low resistance. 7 Series Ohmmeter Shunt Ohmmeter 8 4 Bridge Method †¢ Bridge methods are used for measurement of resistance, capacitance, inductance, etc. †¢ e. g. the network will be balanced when the detector reading becomes zero. Component Being Measured Bridge Network Detector 9 Wheatstone Bridge †¢ DC supply, Vs †¢ Output voltage, Vo B R1 I1 A I2 R3 D + Vs – R4 10 R2 Vo C 5 Wheatstone Bridge (Cont’d) †¢ When Vo = 0, the potential at B must equal to the potential at D I1R1 = I2R3 I1R2 = I2R4 Hence I1R1 = I2R3 = (I1R2/R4) R3 R1/R2 = R3/R4 †¢ The balance condition is independent of Vs 11 Wheatstone Bridge (Cont’d) †¢ R2 and R4 are known-fixed resistances. †¢ R3 can be adjusted to give the zero potential difference condition. †¢ R1 is the input resistance to be measured. A R1 Adjust R3 B Vo = 0 G B D Wheatstone Bridge 12 6 Wheatstone Bridge (Cont’d) †¢ †¢ †¢ †¢ †¢ Change in R1, change R3 Precision about 1 ? to 1 M? Accuracy is up to the known resistors. Sensitivity of the null detector Error comes from changes in resistances by changes in temperatures. 13 Wheatstone Bridge (Cont’d) †¢ If no galvanometer at the output, VAB = Vs R1/(R1+R2) VAD = Vs R3/(R3+R4) Thus, Vo = VAB – VAD Vo = Vs ( R1/(R1+R2) – R3/(R3+R4) ) †¢ The relationship between Vo and R1 is non-linear 14 7 Wheatstone Bridge (Cont’d) †¢ A change R1 to R1+? R1 gives a change Vo to Vo+? Vo Vo+? Vo=Vs((R1+? R1)/((R1+? R1)+R2) – R3/(R3+R4)) Then (Vo+? Vo)–Vo = Vs R1+? R1 – R3 R1+? R1+R2 R3+R4 –Vs R1 – R3 R1+R2 R3+R4 = Vs R1+? R1 – R1 R1+? R1+R2 R1+R2 15 Wheatstone Bridge (Cont’d) †¢ If small changes ? R1 >R3 and Rs1//R3 to Rs1 avoid the leakage effect †¢ Rs2 may affect the R3 R4 detector sensitivity 24 12 Bridge Compensation †¢ The resistance of long leads will be affected by changes in temperatures †¢ To avoid this, 3 leads are required to connect to the coils †¢ They are all the same length and resistance 25 Bridge Compensation (Cont’d) †¢ Any changes in lead resistance will affect all 3 leads equally and occur in 2 arms of bridge and will cancel out. 3 R1 1 2 R3 Vs Vo R4 26 R2 13

Customers' and firms' views of using drones in business Essay

Customers' and firms' views of using drones in business - Essay Example A drone resembles and acts like an airplane. Lack of a pilot flying the drone is the major difference between a drone and an airplane. A person in a certain station controls a drone. The individuals are responsible for monitoring areas covered by the drone. In addition, the individual controls the movement of the drone. Drones are common among the military and army squads as they use them to survey enemies’ movement. They also act as bombs for attacking enemies. Development of drone abilities attracted executives who used for surveying areas that was not within the businessperson reach. Therefore, the drone has been of great service as it save time. Businessperson, use the drone for purposes such as delivery, providing internet services, news, photography, agriculture, population and monitoring public service.1 Apparently, the firms using drone and consumer have different views considering the use of drones in business activities. Some view them as advantageous while some view them as a disturber. Nevertheless, it depends on the service the drone offers to the individual. This paper attempts to views and explains the difference and similarities between the customers and the firm’s view on the usage of drones in business activity. The paper also adds the differences that firms and customers have while viewing the usage of drones in the business. It adds that the difference in people view is the main reason for the difference in how people view drones. Despite the many benefits of using drones in business, some firms and customers complain of the services produced. Some firms view the usage if drone in business and efficient. They lay their view upon the fast services produced when using the drone especially when delivering products. It is clear that most firms have experienced a challenge when delivering products and services to consumers in time when delivering products locally. The main problems that firms experience is a

Growth through Internationalisation among Entrepreneurial Firms Essay

Growth through Internationalisation among Entrepreneurial Firms - Essay Example . The study of internationalization and its effects on growth of entrepreneurial firms have been studied using secondary data from relevant articles. These articles are chosen based on its topic and content, which is relevant in the study of internationalization and its effect on the growth of entrepreneurial companies. Each of the articles is thoroughly analyzed and the information recovered from them is used to discuss its implications on entrepreneurial activities. The journal article by Buckley and Hashai is chosen for its analysis. Their article â€Å"Formalizing internationalization in the eclectic paradigm† is based on an equilibrium model which describes internationalization in the light of competitive advantage. It explains why firms adopt overseas expansion strategies and how it acts on behalf of their growth. The aim and objective of this article are to establish a formalized theory on internationalization in the light of eclectic paradigm by reconfiguring certain ne o-classical economic theories. A set of inequalities has been formulated to establish the role of eclectic paradigm in overseas expansion. The equilibrium is based on the concept of ownership advantage, location advantage, and internalization advantage which has been incorporated into the general equilibrium model, mostly preferred by economists. Foreign Direct Investment (FDI) is explained as an operation model which maximized the utility of workers and entrepreneurs simultaneously. A firm adopts an overseas operation only when the total utility received from FDI activities in a host country is more than the total utility received from the exports, domestic consumption and inward FDI. The three elements of the eclectic paradigm are ownership, location and internalization advantages. These are continuous in nature and often tend to support each other. The decrease in one advantage can be compensated by the other two. These competitive advantages are leveraged by the entrepreneurial firms to enhance their growth overseas and gain an edge over its competitors.

Critical Assessment of Two Music Reviews about 1 CD Term Paper

Critical Assessment of Two Music Reviews about 1 CD - Term Paper Example In her review, Feller recognized ‘The Pursuit’ under an aesthetic criteria based on how Jamie Cullum was able to improvise with the chosen original compositions and her critique feels that Cullum made his own version direct a totally unique course so the music, as in Cole Porter’s ‘Just One of Those Things’ comes out familiar yet strangely phenomenal. The article reflects a cheerful acknowledgment of the ways pop, Broadway, R&B, hip hop, club jams, and classics become ingredients that dish up the album in the fashion Jamie would prefer to give shape to his own rendition of a few covers whose chief elements have not neglected to show their origins even as Cullum placed them on his special diversion (Feller). As such, Feller acclaims ‘I’m All Over It’ which to her sounds both heavy and energetic with piano and drums respectively, so much so that the sad content of the lyrics overpowers and brings a notice less significant than instrument work. According to her, this establishes a good introduction of the musician’s profile and personal selection while ‘Wheels’ was made for the audience to be insightful about the apocalypse in which the abrupt pacing with the piano play makes the lyrical turn highly volatile to affect a listener’s mood with progressive wildness. ‘You and Me are Gone’ in the same manner passed the reviewer’s scrutiny as she takes delight in sounds that pull off the swing in the typical 1940s setting and dance attitude at the time. There even is a point when a jazz waltz by tradition melts with songs that are rather expected to comprise the atmosphere in a chill out lounge. More uplifting remarks are given to ‘Mixtape’ which is a track that’s presumably competent of implying to the audience what ‘The Portrait’ is made of, as in the touch of an inner impression such album ought to be planned by the composer. Within pop tune, Sally’s assessment speaks of a collection that

Does islam permite acting in film and theatre Essay - 1

Does islam permite acting in film and theatre - Essay Example Acting is generally forbidden in Islam but is allowed for certain constructive purposes provided certain conditions are followed. The issue of acting being allowed or forbidden in Islam is a topic of great controversy among the scholars and interpreters of Islam. However there is complete consensus among all the various scholars about the type of acting which involves obscenity, interaction between men and women and other evil actions. All the scholars unanimously agree on the prohibition of this type of acting in Islam. There is no dispute among the Islamic scholars as far as this kind of acting is concerned (Al-Munajjid 2009). The prohibition of this type of acting is clear from the saying of Sheikh Abu Bakr Zayed (may Allah preserve him) to the effect that chivalry (behaving properly and decently) happens to be an objective of sharee’ah, plus whatever undermines that makes a person unsuitable for giving statement in court. Islamic teachings stress upon lofty characteristics and prohibit base and low characteristics. And as far as acting is concerned, actors are mostly seen by the viewers as performing ridiculous activities and moving and talking in a ridiculous way. They are yet seen as feigning madness. Thus it is proven beyond doubt that acting is among those things that seriously undermine chivalry. This further leads to the fact that acting is among those things which make a person unsuitable for giving testimony in the court of law. Such a thing cannot be approved of by Sharee’ah in any way. Now let us consider the type of acting about which there exists a controversy among the scholars of Islam. Some forbid it completely while others allow it within certain guidelines of Sharee’ah. This controversial type of acting is one that involves two or more than two persons performing before a group, through actions and dialogue, with a purpose to teach the group about Islamic principles and injunctions, or

Migration Experience from the west Indies ti the US Essay

Migration Experience from the west Indies ti the US - Essay Example once they reach here are faced with challenges which they have to conquer if they are to have an easy life and eventually succeed in their new environment. This research examines the challenges immigrants go through with the discussion focusing on a family from Haiti. The paper will expound on how immigrants go about in settling in their new homes, general receptiveness of neighbors, race discrimination, jobs, deciding whether to assimilate or acculturate and young ones schools life. Marie Lafont, who is my aunt, migrated to the United States of America from Haiti in 1976, she settled in Brooklyn New York with her husband and three children. The area was predominantly black with a large Haitian community therefore the general reception they got was a warm one. Portes and Rumbaut state that once here, some immigrants enjoy better conditions than back home (18). This is demonstrable in my aunt’s case where the house they were to live in was bigger than what they had been accustomed to back in Haiti. In their new home they had a front yard and the rooms were much larger than what they were used to. Transitioning into their new way of life was not easy with things like speaking English with a French accent being an issue but with the help of the community around them, transitioning was made simpler. Upon their settling down in Brooklyn, my aunt discovered that the race factor was a major problem in the US, an issue that had not crossed her mind back in Haiti and was a major defining factor in her new home. She found out that due to her skin color, certain barriers were erected for example being discriminated against when applying for her nursing job. This new dimension added on to the everyday difficulties she was starting to face. All of a sudden the complexion of her skin became a problem and to make matters worse, this was an issue she had no control over. Through her interaction with her neighbors, she found out that Haitians who had preceded her had faced and

Dance and Daffodils Essay Example for Free

Dance and Daffodils Essay I wandered lonely as a cloud William Wordsworth I wandered lonely as a cloud That floats on high oer vales and hills, When all at once I saw a crowd, A host, of golden daffodils; Beside the lake, beneath the trees,5 Fluttering and dancing in the breeze. Continuous as the stars that shine And twinkle on the milky way, They stretched in never-ending line Along the margin of a bay:10 Ten thousand saw I at a glance, Tossing their heads in sprightly dance. The waves beside them danced; but they Out-did the sparkling waves in glee: A poet could not but be gay,15 In such a jocund company: I gazedand gazedbut little thought What wealth the show to me had brought: For oft, when on my couch I lie In vacant or in pensive mood,20 They flash upon that inward eye Which is the bliss of solitude; And then my heart with pleasure fills, And dances with the daffodils. [pic] Summary The speaker says that, wandering like a cloud floating above hills and valleys, he encountered a field of daffodils beside a lake. The dancing, fluttering flowers stretched endlessly along the shore, and though the waves of the lake danced beside the flowers, the daffodils outdid the water in glee. The speaker says that a poet could not help but be happy in such a joyful company of flowers. He says that he stared and stared, but did not realize what wealth the scene would bring him. For now, whenever he feels vacant or pensive, the memory flashes upon that inward eye / That is the bliss of solitude, and his heart fills with pleasure, and dances with the daffodils. Questions 1.What figure of is found in lines 1 and 7? Which two things are being compared in each case? 2.Quote TWO VERBS from stanza 1 which describe the movement of the daffodils. 3.What mood is created by the words mentioned in questions 2? 4.What is the poet saying about the daffodils when comparing them to the stars in the Milky Way? 5.Which figure of speech is evident in line 12 – â€Å"Tossing their heads in sprightly dance†? 6.What effect do the waves and daffodils have on the poet in stanza 3? 7.Comment on the repetition of the word â€Å"gazed† in line 17. 8.Does the poet use the word â€Å"wealth† literally of figuratively in line 18? Give a reason for your answer. 9.What is the â€Å"inward eye† mentioned in line 21? 10.What effect does the memory of the daffodils have on the poet? Across 2. perfect happiness (stanza 4) 4. valleys (stanza 1) 6. a contraction of the word â€Å"over† (stanza 1) 7. riches (stanza 3) 8. jovial, merry, lighthearted (stanza 3) 9. in a lively and vigorous way (stanza 2) 10. the edge (stanza 2) 12. a brilliant yellow flower (stanza 1) Down 1. to look briefly (stanza 2) 3. state of being alone (stanza 4) 4. not occupied, empty (stanza 4) 5. looking thoughtful (stanza 4) 10. the galaxy in which the earth is located (stanza 2) 11. a large number of items (stanza1)