Practice 7_AFC - Edgar Bello

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Index 
Objective 3 
Equipment 3 
Material 3 
Theoretical introduction 3 
Development of the practice 4 
Questionnaire 9 
Conclusions 10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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I.- OBJECTIVE​. 
The student will apply the method of nodes to determine the voltages present in an 
electrical circuit, so that at the end of the practice, this able to employ this technique 
in the calculation of the voltage drops present in networks that contain multiple 
nodes​. 
II.- MATERIAL EQUIPMENT. 
 
PROVIDED BY THE LABORATORY BY THE STUDENTS 
1 Digital multimeter. 1 Protoboard 
1 variable dc voltage source. 2 Resistors 1kΩ to 1/2 W 
Signal Generator 2 Resistors 120Ω to 1/2 W 
Oscilloscope 1 Ceramic capacitor 0.1x10-6 to 1/2 W 
Banana Plugs. 1 Resistors 560Ω to 1/2 W 
1 Oscilloscope probe BNC-double clips Wire connection to the protoboard 
Nose pliers 
Cutting Pliers. 
 
III.- THEORETICAL INTRODUCTION. 
In this practice is for the student to increase their capacities in the analysis of 
electrical circuits, so that you can calculate the voltages on networks that contain 
multiple nodes. In a nodal analysis is used the LCK to determine the voltages of the 
nodes, which are defined in relation to a common point, or the Reference node in the 
circuit under analysis. Often this node is one to which you are connected to the 
greatest number of branches and to which it is commonly referred to as the earth 
because it is said to be a potential ground zero, and sometimes represents the 
chassis or earth line in a practical circuit. In this type of analysis, the variables in the 
circuit is chosen as the voltages of the nodes. These variables are selected as 
positive with respect to the reference node, so that if any of the voltages of the nodes 
really is negative with respect to the reference node, the analysis will show this. 
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Since the existence of a voltage is defined between two nodes, the node reference 
you must associate a voltage with each of the other nodes, and the voltage at each 
different node with respect to the reference is defined as a voltage of node, node at 
the point of connection of two or more circuit elements. In a circuit containing N 
nodes, there will be N-1 node voltages to determine, through the application of 
Kirchhoff's current law to the N-1 nodes circuit, giving us N-1 equations linearly 
independent. As shown in figure 1. 
 
IV.- DEVELOPMENT OF THE PRACTICE. 
 
Applying the node method to the circuit in Figure 2, find using theoretical method 
(analytical method), the corresponding rms current values ​​that are ask in the specific 
points and write them down in table 1. 
 
2. Without turning on even the voltage source, assemble the circuit of figure 2, on the 
breadboard. Once armed, proceed to set the value of the rms voltage and frequency 
indicated and apply to the circuit, through the tips of the Cayman Islands-banana 
test, the source of power. 
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3. Check the validity of their previous theoretical results by measuring, with the 
ammeter, the rms current in the points made above and report their practical values 
in Table 1. 
 
Measurements 
 
 
Simulation value 
 
 
Current ​I 
 
4.828 ​mA 
 
Current ​II 
 
41.666 ​mA 
Current​ I0 
 
4.77 ​mA 
 
TABLE 1. VALUES OF CURRENT 
 
4. From the same circuit, get the values of rms, and report them in Table Num. 2 
 
 
 
Measurements 
 
 
Simulation value 
 
 
Voltage ​I 
 
749.38 ​mV 
 
Voltage ​II 
 
5 ​V 
Voltage ​I0 
 
4.828 ​V 
 
TABLE 2. VALUES OF VOLTAGE 
5. Finally, calculate the average power dissipated by each resistor and write it down 
on the table 3. 
 
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Resistance 
 
Dissipating average power 
(Watts) 
 
 
R1 
 
3.618 ​mW 
 
R2 
 
0.20833 ​W 
R3 
 
0.023 ​W 
 
Simulations. 
*Current 
 
 
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*Voltage 
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V.- Questionnaire. 
1. Define what is a node in an electrical circuit. 
A node is a point where two or more electrical components have a common 
connection. 
 
2. Define node voltage 
The potential difference between the measured node and a reference node whose 
voltage is zero. 
 
3. What is called a reference node? 
Is the node where the ground is located, its voltage value equals zero. 
 
4. Briefly describe what the node voltage method consists of. 
In the node voltage method, a node is named as a reference node, after that, a 
group of equations must be formulated using the currents entering and leaving each 
node according to LCK, and finally a system of equations, whose unknowns are the 
voltage values, is generated using Ohm’s law. 
 
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VI .- Conclusions. 
 
Bello Muñoz Edgar Alejandro 
The node voltage method is a good alternative to the mesh method because it allows 
to calculate the voltage in different areas the same kind of circuits, in a way that it is 
possible to have the same results and find the whole information of all the circuit 
components, using already known topics as Ohm's law and Kirchhoff's laws for 
current and voltage. 
 
Núñez González Ángel Daniel 
Node analysis is one of the most important topics in this matter, since with this we 
can obtain resolutions to complex circuits and that is crucial in this environment, this 
is because many of the circuits that are worked both theoretically and in a practical 
way they have nodes and being able to solve them through them is something very 
valuable. It should be noted that however advanced the subject is, the ohm law and 
Kirchhoff's laws are still used, without a doubt nothing is wasted in this subject. 
 
López Gracia Angel Emmanuel 
In this practice we learned a new technique to analyze circuits, nodes analysis 
seems to be quite my favorite circuit method of analysis so far, not just because it is 
easy, but because it is related very close to Ohm’s and Kirchhoff's Laws, also it is 
intuitive, I will probably use it in the future as electric problems get more and more 
complex. I hope to win more practice while the future passes. 
 
 
 
 
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