Chapter 2-2
•Nodes and Paths
•KCL and KVL
Node
A node: is a point where two or more circuit elements
meet.
Kirchhoff’s Current Law (KCL): This law states that the
algebraic sum of the currents at a node must be equal
to zero.
Our sign convention will be:
Assign a negative sign to a current entering a node
Assign a positive sign to a current leaving a node
i3
i
i2
i1
Find I1, I2, and I3.
I1
200mA
+
500mA
–
100mA
I2
I3
50mA
R1
R2
R3
R4
Closed Path or Loop
A closed path: Starting at an arbitrary node we trace a
path through selected circuit elements and return to the
original node, without passing through any single point
more than once
Kirchhoff’s Voltage Law (KVL): states that for any closed loop in
a circuit, the algebraic sum of the voltages around the loop must
be equal to zero.
10 Ohm
10 Ohm
10 V
A
20 Ohm
B
Find io and voltage across 50 ohm
Find vo using Kirchhoff’s laws and Ohm's law. vs = 10 V
Find the value of ia. Given vg = 40 V , Rg = 3 Ω , Ra = 30 Ω , and Rb =
100 Ω
Circuits with Dependent Sources
Find vo
Find vo
Find vo
What you should know
1.
2.
KCL and KVL
Application of them
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