Assessment Problem # 4.1
ECE 201 Circuit Theory I
1
Use the node-voltage method to find
v1, v2, and i1
R3
5 Ohm
+
I1
15 A
v1
R1
60 Ohm
R2
15 Ohm
i1
-
+
R4
2 Ohm
v2
I2
5A
-
ECE 201 Circuit Theory I
2
Identify the voltages and currents
v1
v2
R3
5 Ohm
I1
15 A
i3
R1
60 Ohm
i2
R2
15 Ohm
i1
ECE 201 Circuit Theory I
i4
R4
2 Ohm
I2
5A
3
Write KCL at each node
v1
v2
R3
5 Ohm
I1
15 A
i3
R1
60 Ohm
i2
R2
15 Ohm
i1
i4
R4
2 Ohm
I2
5A
v1 v1 v1 - v 2
+ +
= 15
60 15
5
v 2 v 2 - v1
+
= -5
2
5
ECE 201 Circuit Theory I
4
v1
R3
v2
5 Ohm
I1
15 A
R1
60 Ohm
R2
15 Ohm
R4
2 Ohm
I2
5A
1 1
 1
 1
v1  + +  - v 2   = 15
 60 15 5 
5 
 1
 1 1
-v1   + v 2  +  = -5
5 
2 5
ECE 201 Circuit Theory I
5
Solving
R3
5 Ohm
+
I1
15 A
v1
R1
60 Ohm
R2
15 Ohm
i1
-
+
R4
2 Ohm
v2
I2
5A
-
v1 = 60V
v 2 = 10V
v1 - v 2 50
i1 =
=
= 10A
5
5
ECE 201 Circuit Theory I
6
How much power is delivered
by the current sources?
R3
5 Ohm
I1
15 A
+
60V
R1
60 Ohm
R2
15 Ohm
R4
2 Ohm
+
10V
I2
5A
-
-
P15A = VI = (60V)(15A) = 900W
P5A = VI = -(10V)(5A) = -50W
ECE 201 Circuit Theory I
7