Electrical Resistance

JMJ MARIST BROTHERS NOTRE DAME OF DADIANGAS UNIVERSITY MARIST AVENUE, GENERAL SANTOS CITY MULTITESTER Instrumentation and Control CpE 511 NAME KURT RUSSEL C. CHUASeptember 01, 2012 CYNTHIA C. GONZAGADate of Submission INSTRUCTOR ENGR. JAY S. VILLAN, MEP-EE Introduction A multitester or multi molarity is a thingummy which can be used to gather data about electrical sets. A basic multitester can measure resistance, voltage, and continuity while more advanced versions may be able to provide additional data.This tool can be very useful to drop around the house, and anyone who plans on doing electrical repairs should around definitely use a multitester for safety campaigns. Multitesters can be used with the current off or on in most cases, although using the braid with the current on can some clock times result in damage to the device. Theory Ammeters are employed for measuring current in a circuit and connected in series with the circuit. As ammeter is connected in series, the vo ltage drop across ammeter terminals should be as low 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 metric 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 ii points of the circuit these are connected in the parallel to the circuit. The resistance of voltmeter is kept 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 through a mechanical meter movement which operates on electric current. Th e ohmmeter must then have an internal source of voltage to create the necessary current to operate the movement, and also have appropriate ranging resistors to allow just the right amount of current through the movement at any given resistance.One major problem with this design is its combine upon a stable battery voltage for accurate resistance reading. If the battery voltage decreases, the ohmmeter scale will lose accuracy. Conclusion Aside from using devices such(prenominal) asmultitester, the resistance value of aresistor can be determined by its color 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 a good deal easier to read the resistance value of a resistor through a digital multitester than by using an analog multitester and by color coding. In addition, in using an analog multiteste r, you have to first consider the range of the resistance and make the zero-ohm adjustment in each and every 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 ?