1. ECE 1270: Introduction to Electric Circuits
Lecture 5:
Node Analysis
Chapter 4
Techniques of Circuit Analysis: Sections 4.1,4.2

2. Node, Branch, Loop, Mesh Branch Node (current sum) Mesh (voltage sum)
Node: A point where two or more circuit elements join
Mesh: A loop that does not enclose any other loops
Branch: A circuit path that contains two nodes
Loop: A path with many meshes. Example: V1-R1-R5-R6-R4-V2

3. Nodes: More Examples
Remember that node is not a just a dot; it represents
common connection between different circuit elements

4. Nodes in an Actual Circuit
Can you identify nodes in the above circuit?

5. Step2: Define Node Voltages
Node Voltage Method
Find unknown voltages by summing the currents leaving each node
Example 4.2
Step1: Label Nodes
Step2: Define Node Voltages

6. Node Voltage Method Step3: Write Current Leaving Each Branch
Passive Sign Convention
Step4: Solve Simultaneous Equations in Standard Form

7. Passive Sign Convention
AP4.1a: Find v1, v2, i1
Simultaneous Equations:
Passive Sign Convention
Solution
v1= v2= i1=
System of Linear Equations: learn how to solve it using your calculator

8. Passive Sign Convention
AP4.2: Find v + v -
Simultaneous Equations:
Passive Sign Convention
Students do this example
Solution v=
System of Linear Equations: learn how to solve it using your calculator

9. Passive Sign Convention
Simultaneous Equations:
Passive Sign Convention
Students do this example
Solution
System of Linear Equations: learn how to solve it using your calculator

10. Lab 4 Circuit
Lab 4: Find Vx using Node Voltage Method