Krichoff's Voltage Law Essay

379 WordsNov 15, 20112 Pages
Introduction In this experiment we will analyze two very common circuits configuration: series resister and parallel resisters. we will se that series resistors acts like a "voltage divider," and parallel resistors act like a "current divider." Also series and parallel resistors provide equivalent currents. In the figure 1 below three resistors R1, R2 and R3 are in series. with a voltage source on the left. Kirchoff's Voltage Law states that the sum of voltage around a loop is equal to zero. Now form the loop in figure one we can say that; - Vs +V1 + V2 + V3 = 0 Where V1, V2 and V3 are voltage across resistors R1, R2 and R3. since the current across the series loop is always the same current across each resistor is Is. Vs = V1+V2 +V3 Vs = Is.R1 + Is.R2 +Is.R3 Req = R1 +R2 +R3 [pic] Kirchoff's current Low Kirchoff's Current Low states the sum of the currents leaving or entering a node is equal to zero. Now if we consider a circuit in figure 2 where 3 resistors R1, R2 and R3 are in parallel with a voltage source. The voltage across each of the resistors will be the same but the currents divides. Considering the single node circuit illustrated in figure 2. KCL for Parallel resistors -Is + I1 +I2 + I3 = 0 Is = I1 +I2 + I3 Is = V / R1 + V / R2 + V / R3 or, Is / V = 1 / R1 + 1 / R2 + 1 /R3 or, 1/ R eq = 1 / R1 + 1 / R2 + 1 /R3 [pic] Procedure 1. The equivalent Resistance of each figure 4A, 4B and 4C are calculated. 2. Each of the resistors in the figure 4A, 4B and 4C are set up seperately and equivalent voltage was measured using ohmmeter. Each measured resistors are recorded in the table 1. 3. In the figure below X represent the 5 volt applied and Y represent the ground. Then current was calculated for each figure and measured using ammeter in table 1. 4. Each resistors in each figure was replaced by equivalent voltage using Decade Box

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