Nodal Analysis: Understanding Method & Solving for Unknown Voltage

In summary, the conversation is about nodal analysis and how to properly consider each node when using this method. The speaker points out that the first equation used did not include the current through the 75V voltage source and should have been (75-Vx)/2 -10 -(i3+0.4*Vx)= 0. The expert also explains that when doing nodal analysis, it is important to only do KCLs at nodes with unknown voltages and to keep in mind the known voltage of the 75V node. After making these adjustments, the solution becomes clearer.
  • #1
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I understand their method. However, if you use the node to the left of the 2 ohm resistor (the node where the voltage = 75 V) then you get:

(75-Vx)/2 -10 = 0

so 75-Vx = 20
so Vx - 75 = -20
Vx = 55 V

But this is not 25 V as it should be?

When doing nodal analysis, do you have to consider each node?
 
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  • #2
You did not include the current through the 75 v voltage source. your first equation should have been
(75-Vx)/2 -10 -(i3+0.4*Vx)= 0

that being said when you do nodal analysis you should only do kcl's at nodes with unknown voltages. you know that the 75v node is 75 v above ground. So try a KCL at nodes Vx and V1

does that make sense?
 
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  • #3
donpacino said:
You did not include the current through the 75 v voltage source. your first equation should have been
(75-Vx)/2 -10 -(i3+0.4*Vx)= 0

that being said when you do nodal analysis you should only do kcl's at nodes with unknown voltages. you know that the 75v node is 75 v above ground. So try a KCL at nodes Vx and V1

does that make sense?

Ah yes! Thanks a lot mate.
 

FAQ: Nodal Analysis: Understanding Method & Solving for Unknown Voltage

1. What is nodal analysis and how does it work?

Nodal analysis is a method used in electrical circuit analysis to determine the voltage and current at each node in a circuit. It works by applying Kirchhoff's current law at each node in the circuit and using Ohm's law to solve for the unknown voltages.

2. When should nodal analysis be used?

Nodal analysis should be used when solving for multiple unknown voltages in a circuit with both current and voltage sources. It is also useful for circuits with multiple loops, as it can simplify the analysis process.

3. What are the advantages of using nodal analysis?

The main advantage of using nodal analysis is that it can simplify complex circuits into a system of linear equations, making it easier to solve for unknown voltages. It also allows for a systematic and organized approach to circuit analysis.

4. What are the limitations of nodal analysis?

One limitation of nodal analysis is that it can become cumbersome and time-consuming for circuits with a large number of nodes. It also assumes that all components in the circuit are linear, which may not always be the case.

5. How do you choose the reference node in nodal analysis?

The reference node in nodal analysis is typically chosen as the node with the most connections to other nodes in the circuit. This makes it easier to write equations and solve for unknown voltages. However, any node in the circuit can be chosen as the reference node as long as the equations are written consistently.

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