Kirchhoff’s Laws for Resistive Circuits
Kirchhoff developed some useful rules for the analysis of resistive circuits.
These are
known as Kirchhoff’s Junction Law (think of current), and Kirchhoff’s Loop Law (think
of voltage).
Consider first the circuit shown below.
Given the values of a certain number
of the circuit’s elements, we can find the remaining unknowns with the application of one
of Kirchhoff’s laws.
Here, the voltages, and resistances are all known, but we are left to determine the currents
I
1
, I
2
, and I
3
.
It is useful to mark in all the directions of the given currents and voltages on
the circuit.
d
f
e
c
b
a
I
2
V
2
=60V
v
1
=100V
I
1
R
4
=6
Ω
R
2
=12
Ω
R
3
=4
Ω
I
2
I
3
R
1
=10
Ω
I
1

+

+
I
3
Kirchhoff’s Junction Law:
The algebraic sum of all currents into any junction is
zero
.
By a junction, we mean any
set of terminals such as,
a, b, c, d, e
, and
f
, as shown in the figure which are connected.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '07
 Pottebaum
 Addition, Electric charge, The Circuit, Kirchhoff's circuit laws, Kirchhoff

Click to edit the document details