Download Experiment No. (3) Parallel DC Circuits and more Slides Law in PDF only on Docsity! ELECTRICAL CIRCUIT LABORATORY Experiment No. (3) Parallel DC Circuits Objective The focus of this exercise is an examination of basic parallel DC circuits with resistors. A key element is Kirchhoff’s Current Law which states that the sum of currents entering a node must equal the sum of the currents exiting that node. The current divider rule will also be investigated. Theory Overview A parallel circuit is defined by the fact that all components share two common nodes. The voltage is the same across all components and will equal the applied source voltage. The total supplied current may be found by dividing the voltage source by the equivalent parallel resistance. It may also be found by summing the currents in all of the branches. The current through any resistor branch may be found by dividing the source voltage by the resistor value. Consequently, the currents in a parallel circuit are inversely proportional to the associated resistances. An alternate technique to find a particular current is the current divider rule. For a two resistor circuit this states that the current through one resistor is equal to the total current times the ratio of the other resistor to the total resistance. Equipment (1) Adjustable DC Power Supply (1) Digital Multimeter (1) 1 kΩ __________________ (1) 2.2 kΩ __________________ (1) 3.3 kΩ __________________ (1) 6.8 kΩ __________________ ELECTRICAL CIRCUIT LABORATORY Schematics Figure 3.1 Figure 3.2 Procedure 1. Using the circuit of Figure 3.1 with R1 = 1 k, R2 = 2.2 k and E = 8 volts, determine the theoretical voltages at points A, B, and C with respect to ground. Record these values in Table 3.1. Construct the circuit. Set the DMM to read DC voltage and apply it to the circuit from point A to ground. The red lead should be placed at point A and the black lead should be connected to ground. Record this voltage in Table 3.1. Repeat the measurements at points B and C. 2. Apply Ohm’s law to determine the expected currents through R1 and R2. Record these values in the Theory column of Table 3.2. Also determine and record the total current. 3. Set the DMM to measure DC current. Remember, current is measured at a single point and requires the meter to be inserted in-line. To measure the total supplied current place the DMM between points A and B. The red lead should be placed closer to the positive source terminal. Record this value in Table 3.2. Repeat this process for the currents through R1
