Electrical Resistance

JMJ MARIST BROTHERS NOTRE DAME OF DADIANGAS UNIVERSITY MARIST AVENUE, GENERAL SANTOS CITY MULTITESTER Instrumentation and Control CpE 511 relieve oneself KURT RUSSEL C. CHUASeptember 01, 2012 CYNTHIA C. GONZAGADate of Submission INSTRUCTOR ENGR. JAY S. VILLAN, MEP-EE Introduction A multitester or multimeter is a tress which empennage be employ to gather data about electric circuits. A basic multitester can measure resistance, potency, and continuity while more than advanced versions may be able to provide additional data.This pricking can be very useful to have around the house, and bothone who plans on doing electrical repairs should most definitely use a multitester for safety reasons. Multitesters can be used with the original off or on in most cases, although using the device with the current on can sometimes result in damage to the device. Theory Ammeters are employed for measurement current in a circuit and connected in serial publication with the circuit. As ammeter is connected in series, the voltage drop crossways ammeter terminals should be as first base as possible.This requires that the resistance of the ammeter should be as low as possible. The current coil of ammeter has low current carrying capacity whereas the current to be mensural may be quite high. For this reason a low resistance is connected in parallel to the current coil. Voltmeters are employed to measure the potential difference across any devil points of the circuit these are connected in the parallel to the circuit. The resistance of voltmeter is unploughed very high by connecting a high resistance in series of the voltmeter with the current coil of the instrument.The actual voltage drop across the current coil of the voltmeter is only a fraction of the total voltage applied across the voltmeter which is to be measured. An ohmmeter is a measuring instrument used to measure the resistance placed between its leads. The resistance reading is indicated by a mechanical met er movement which operates on electric current. The ohmmeter must(prenominal) then have an internal source of voltage to create the necessary current to operate the movement, and also have appropriate ranging resistors to allow on the nose the right amount of current through the movement at any given resistance.One major problem with this design is its reliance upon a changeless battery voltage for accurate resistance reading. If the battery voltage decreases, the ohmmeter outgo will lose accuracy. Conclusion Aside from using devices such(prenominal) asmultitester, the resistance valuate of aresistor can be opinionated by its blazon coding. There are small differences between measured and color coded values of the resistances. These differences may be caused by some factors such as the multitester used in the experiment and some mistakes made by the experimenters.It is much easier to read the resistance value of a resistor through a digital multitester than by using an anal og multitester and by color coding. In addition, in using an analog multitester, you have to first pick out the range of the resistance and make the zero-ohm adjustment in each and either reading. In that case, that is the only time youcan acquire the resistance value after aslight inconvenient process. Pictorial Calculation For Ammeter * 0. 25A R1=99mV0. 25A R1= 0. 96 ? * 25mA R2=99mV25mA-R1 R2= 3. 564 ? * 2. 5mA R3=99mV2. 5mA-R2-R1 R3= 35. 64 ? For DC Voltmeter * 2. 5V R1=2. 5V49. 5A-Rm R1= 48, 505. 05051 ? * 10V R2=10V49. 5A-Rm-R1 R2= 151,515. 1515 ? * 50V R3=50V49. 5A-Rm-R1-R2 R3= 808,080. 8081 ? For AC Voltmeter * 10V Im=49. 5A0. 637 Im= 77. 70800628A R1=1. 41410-1. 477. 70800628A-Rm R1=161,947. 0707 ? * 25V R2=1. 41425-1. 477. 70800628A-Rm R2= 434,891. 9192 ? * 250V R3=1. 414250-1. 477. 70800628A-Rm R3= 4,529,064. 646 ?