Kirchhoff’s Current and Voltage Laws

KCL (Kirchhoff’s Current Law)

The sum of the currents entering a node equals the sum of the currents exiting

a node.

Node

Application of KCL

I1 = 2A

I2 = 3A

I3 = 5A

I1 = ?

I2 = 150 mA

I3 = 250 mA

Problem w/KCL

KVL (Kirchhoff’s Voltage Law)

The sum of the potential differences around a

closed loop equals zero.

Closed Loop #1

Closed Loop #2

Closed Loop #3

Closed Loop #4

Not Closed #1

Not Closed #2

What KVL Really Means

Sum of the Voltage drops across resistors equals the Supply Voltage in a Loop.

KVL #1

KVL #2