Math Problem Statement

Write down the node-voltage matrix equation for the given circuit.

Solution

To solve this circuit problem using the node-voltage method, we will first label the nodes and then derive the matrix equation using Kirchhoff's Current Law (KCL).

Here are the steps to follow:

  1. Node labeling:

    • There are three nodes in this circuit (excluding the reference ground), which we will call V1V_1, V2V_2, and V3V_3.
    • The reference ground is usually connected to the negative terminal of the circuit.
  2. KCL Equations: At each node, we apply KCL: the sum of currents leaving the node is equal to the sum of currents entering the node.

Node 1 (V1V_1):

For node V1V_1:

  • There are resistances 1Ω (to the 3A source), 5Ω (to node V2V_2), and 10Ω (to node V3V_3).
  • The 5A current source directly enters node V1V_1.

Applying KCL at V1V_1:

V101+V1V25+V1V310=5\frac{V_1 - 0}{1} + \frac{V_1 - V_2}{5} + \frac{V_1 - V_3}{10} = 5

Node 2 (V2V_2):

For node V2V_2:

  • There are resistances 5Ω (to node V1V_1), 8Ω (to node V3V_3), and 4Ω (to ground).
  • The 1A current source directly enters node V2V_2.

Applying KCL at V2V_2:

V2V15+V2V38+V204=1\frac{V_2 - V_1}{5} + \frac{V_2 - V_3}{8} + \frac{V_2 - 0}{4} = 1

Node 3 (V3V_3):

For node V3V_3:

  • There are resistances 10Ω (to node V1V_1), 8Ω (to node V2V_2), and 2Ω (to ground).
  • The 4A current source directly enters node V3V_3.

Applying KCL at V3V_3:

V3V110+V3V28+V302=4\frac{V_3 - V_1}{10} + \frac{V_3 - V_2}{8} + \frac{V_3 - 0}{2} = 4

Matrix Form:

These equations can now be expressed in matrix form as follows:

\frac{1}{1} + \frac{1}{5} + \frac{1}{10} & -\frac{1}{5} & -\frac{1}{10} \\ -\frac{1}{5} & \frac{1}{5} + \frac{1}{8} + \frac{1}{4} & -\frac{1}{8} \\ -\frac{1}{10} & -\frac{1}{8} & \frac{1}{10} + \frac{1}{8} + \frac{1}{2} \end{pmatrix} \begin{pmatrix} V_1 \\ V_2 \\ V_3 \end{pmatrix} = \begin{pmatrix} 5 \\ 1 \\ 4 \end{pmatrix}$$ Now we can simplify the values for each element in the matrix: $$\begin{pmatrix} 1.3 & -0.2 & -0.1 \\ -0.2 & 0.575 & -0.125 \\ -0.1 & -0.125 & 0.725 \end{pmatrix} \begin{pmatrix} V_1 \\ V_2 \\ V_3 \end{pmatrix} = \begin{pmatrix} 5 \\ 1 \\ 4 \end{pmatrix}$$ This is the **node-voltage matrix equation** for the given circuit. Would you like further details on solving this matrix or any other part of the process? --- Here are 5 questions to expand the discussion: 1. What is Kirchhoff's Current Law, and how does it apply to circuit analysis? 2. How do you determine which nodes are essential for node-voltage analysis? 3. Why do we use the node-voltage method instead of mesh analysis for certain circuits? 4. How can you solve the matrix equation obtained in node-voltage analysis? 5. What are the implications of dependent and independent sources in node-voltage analysis? **Tip**: When writing KCL equations, always ensure that you're consistent with the direction of currents (whether entering or leaving the node) to avoid sign errors.

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Math Problem Analysis

Mathematical Concepts

Circuit Analysis
Node-Voltage Method
Kirchhoff's Current Law

Formulas

Ohm's Law: V = IR
Kirchhoff's Current Law: Sum of currents entering a node equals sum of currents leaving the node

Theorems

Kirchhoff's Current Law

Suitable Grade Level

University level (Electrical Engineering)