electrical circuits lab 7

7/31/2019 Electrical Circuits Lab 7

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Objectives:

To mathematically predict the currents and voltages of a circuit by use of mesh and nodalanalysis.

To compare the calculated and measures values. To observe ammeter loading.

Introduction:

The purpose of this experiment was to gain experience using both nodal and mesh

analysis. Once done, the results from each were to be compared. The circuit used for the

calculations was then to be built, and the values were to be measured. These measured results

were then to be compared to the calculated results.

Procedure (Calculated):

The various values labeled on the circuit in Figure 1 of the lab report were recorded.

First, the values were used to set up the mesh analysis calculations. The calculations were done

by assuming each loop to be in the clockwise position. The results of these calculations were

recorded in Table 1 (see results section). The nodal analysis equations were then set up for the

same circuit. Upon completion, the results were found to be the same as those of the mesh

analysis. These results were recorded in Table 1.


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Procedure (Measured):

The circuit in Figure 1 of the lab report was assembled using the given resistor values

(see Figure 1 in results section for diagram with exact used values) and two power supply units.

The various currents and voltages were calculated using a digital multi-meter, and the results

were recorded in Table 1 (see results section). For each current measurement, various range

settings were used to observe ammeter loading. These results were then recorded in Table 2 (see

results section). Afterwards, the percent error was calculated by comparing the measured results

to both the mesh and nodal results. The results of these calculations were recorded in Table 1.

Equipment Used:

ItemMFG'S

Name

Model

#

NHCTC

OR

SERIAL #

DMM Keithley 361885 94850Digibridge GenRad 88446

Power SupplyHewlett

Packard94952

E1

10 V

E2

5 V

R1

46.87k

R2

2.17R3

465.53

Figure 1


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Results:

Table 1

Parameter

Mesh Analysis

Calculations

(Using Nominal

R Values)

Nodal Analysis

Calculations

(Using Nominal

R Values)

Measured

Data

% Error

Measured

vs.

Mesh

% Error

Measured

vs.

Nodal

IR1 0.19 mA 0.19 mA 0.11 mA 42.1 42.1

IR2 -1.84 mA -1.84 mA -2.30 mA 25.0 25.0

IR3 2.03 mA 2.03 mA 2.15 mA 5.9 5.9

VR1 9.05 V 9.05 V 5.03 V 44.4 44.4

VR2 1.90 V 1.90 V 0.12 V 93.7 93.7

VR3 4.05 V 4.05 V 5.11 V 26.2 26.2

Table 2

DMM Range Settings

Parameter 200 A Range 2 mA Range 20 mA Range

IR1 104.9 0.106 0.10

IR2 -1 -1 -2.30

IR3 1 1 1


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Conclusion:

This lab was a very clear demonstration of the amount of effort that both mesh and nodal

analysis take, and clearly shows that each method returns the same results. This is beneficial due

to the fact that it means both methods are equally suitable dependent on preference. The results

found for both the mesh and nodal calculations were exactly identical. The measured results,

however, varied somewhat significantly. The high % error between the measured and calculated

results could be due to several possible factors. One, which is the most likely, is the fact that the

color-coded and measured values of the resistors were not identical. Another factor is the internal

resistance of the instruments being used, which is not accounted for in calculations. The results

of the ammeter loading observations also helped stress the importance of using the correct scale

when taking measurements, as being in the wrong scale can drastically alter your results (mainly

be reducing efficiency). All in all, the objectives of the lab were met through calculations,

measurements, and comparisons.

Sample Calculations:

See hand-written calculations attached at end of lab report.

electrical circuits lab 7

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