# 3.6.4: Procedure

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1. Consider the circuit of Figure 7.3.1 with R1 = 1 k, R2 = 2.2 k, R3 = 4.7 k and E = 10 volts. R2 is in parallel with R3. This combination is in series with R1. Therefore, the R2, R3 pair may be treated as a single resistance to form a series loop with R1. Based on this observation, determine the theoretical voltages at points A, B, and C with respect to ground. Record these values in Table 7.5.1. Construct the circuit. Set the DMM to read DC voltage and apply it to the circuit from point A to ground. Record this voltage in Table 7.5.1. Repeat the measurements at points B and C, determine the deviations, and record the values in Table 7.5.1.

2. Applying KCL to the parallel sub-network, the current entering node B (i.e., the current through R1) should equal the sum of the currents flowing through R2 and R3. These currents may be determined through Ohm’s law and/or the current divider rule. Compute these currents and record them in Table 7.5.2. Using the DMM as an ammeter, measure these three currents and record the values along with deviations in Table 7.5.2.

3. Consider the circuit of Figure 7.3.2. R2, R3 and R4 create a series sub-network. This sub-network is in parallel with R1. By observation then, the voltages at nodes A, B and C should be identical as in any parallel circuit of similar construction. Due to the series connection, the same current flows through R2, R3 and R4. Further, the voltages across R2, R3 and R4 should sum up to the voltage at node C, as in any similarly constructed series network. Finally, via KCL, the current exiting the source must equal the sum of the currents entering R1 and R2.

4. Build the circuit of Figure 7.3.2 with R1 = 3.3 k, R2 = 2.2 k, R3 = 4.7 k, R4 = 6.8 k and E = 20 volts. Using the series and parallel relations noted in Step 3, calculate the voltages at points B, C, D and E. Measure these potentials with the DMM, determine the deviations, and record the values in Table 7.5.3.

5. Calculate the currents leaving the source and flowing through R1 and R2. Record these values in Table 7.5.4. Using the DMM as an ammeter, measure those same currents, compute the deviations, and record the results in Table 7.5.4.

## 7.4.1: Simulation

6. Build the circuit of Figure 7.3.1 in a simulator. Using the virtual DMM as a voltmeter determine the voltages at nodes A, B and C, and compare these to the theoretical and measured values recorded in Table 7.5.1.

7. Build the circuit of Figure 7.3.2 in a simulator. Using the DC Operating Point simulation function, determine the voltages at nodes B, C, D and E, and compare these to the theoretical and measured values recorded in Table 7.5.3.

3.6.4: Procedure is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by James M. Fiore.