Voltage: Ohms Law And Kirchhoffs Rules :: essays research papers

Voltage Ohms Law and Kirchhoffs RulesABSTRACTOhms Law and Kirchhoffs rules is fundamental for the understanding ofdc circuit. This experiment proves and envision how these rules can be applied toso simple dc circuits.INTRODUCTIONIn the theory of Ohms Law, voltage is simply proportional to current asillustrated in the proportionality, V=RI. As shown in this relation, Vrepresent voltage which is the potential difference across the two ends of a voltaical conductor and between which an electric current, I, will flow. Theconstant, R, is called the conductors resistance. Thus by the Ohms Law, onecan determine the resistance R in a DC circuit without measuring it directlyprovided that the be variable V and I is known.A resistor is a piece of electric conductor which obeys Ohms Law andhas been designed to have a specific determine for its resistance. As an extensionof the Ohms Law, two more relationship can be drawn for electric circuitscontaining resistors connected in series or/and parallel. For resistorsconnected in series, the sum of their resistance is, RTOTAL=R1+R2+ ..... +Rn .And for resistors connected in parallel, 1/RTOTAL==1/R1+1/R2+ ..... +1/Rn .Complex dc circuit involving a crew of parallel and series resistors canbe analyzed to find the current and voltage at each point of the circuit using 2 introductory rules formulated by Kirchhoff. 1) The algebraic sum of current at anybranch point in a circuit is zero. 2) The algebraic sum of potential difference,V, around any closed loop in a circuit is zero. These rules and equationsprovided by the Ohms law and the Kirchhoff rule can be experimentally testedwith the implement available in the labEXPERIMENTAL METHODThe apparatus used in the experiment includes a Voltmeter, an Ammeter,some connecting wires and a series of resistors and light incandescent lamp with variesresistance. This experiment could be divided into 5 sections which value ofvoltage and current measured is noted in all sections for furthe r calculation.In the first section, in order to evaluate the reliability of Ohms law, a dccircuit was constructed as FIG 2 (on p.4 ) using a resistor with an judgeresistance at 2400W*120W. In the second section, we were instructed todetermine the internal resistance of the voltmeter. Two dc circuit wereconstructed as FIG 1. and FIG 2. using a resistor with an expected resistance at820000W*41000W. In the third section, we were asked to judge if the filamentof a light bulb obey Ohms law, this was done by constructing a dc circuit asFIG 1. with a light bulb instead of a resistor.