Saturday, July 20, 2019
Voltage: Ohms Law And Kirchhoffs Rules :: essays research papers
Voltage: Ohm's Law and Kirchhoff's Rules ABSTRACT Ã Ã Ã Ã Ã Ohm's Law and Kirchhoff's rules is fundamental for the understanding of dc circuit. This experiment proves and show how these rules can be applied to so simple dc circuits. INTRODUCTION Ã Ã Ã Ã Ã In the theory of Ohm's Law, voltage is simply proportional to current as illustrated in the proportionality, V=RI. As shown in this relation, V represent voltage which is the potential difference across the two ends of a electrical conductor and between which an electric current, I, will flow. The constant, R, is called the conductor's resistance. Thus by the Ohm's Law, one can determine the resistance R in a DC circuit without measuring it directly provided that the remaining variable V and I is known. Ã Ã Ã Ã Ã A resistor is a piece of electric conductor which obeys Ohm's Law and has been designed to have a specific value for its resistance. As an extension of the Ohm's Law, two more relationship can be drawn for electric circuits containing resistors connected in series or/and parallel. For resistors connected 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 combination of parallel and series resistors can be analyzed to find the current and voltage at each point of the circuit using 2 basic rules formulated by Kirchhoff. 1) The algebraic sum of current at any branch 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 equations provided by the Ohm's law and the Kirchhoff rule can be experimentally tested with the apparatus available in the lab EXPERIMENTAL METHOD Ã Ã Ã Ã Ã The apparatus used in the experiment includes a Voltmeter, an Ammeter, some connecting wires and a series of resistors and light bulb with varies resistance. This experiment could be divided into 5 sections which value of voltage and current measured is noted in all sections for further calculation. In the first section, in order to evaluate the reliability of Ohm's law, a dc circuit was constructed as FIG 2 (on p.4 ) using a resistor with an expected resistance at 2400W*120W. In the second section, we were instructed to determine the internal resistance of the voltmeter. Two dc circuit were constructed as FIG 1. and FIG 2. using a resistor with an expected resistance at 820000W*41000W. In the third section, we were asked to judge if the filament of a light bulb obey Ohm's law, this was done by constructing a dc circuit as FIG 1. with a light bulb instead of a resistor.
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