1. Page 107 of the text by Nilsson and Riedel
Assessment Problem #4.7
Page 107 of the text by
Nilsson and Riedel
ECE 201 Circuit Theory I

2. Determine the power delivered by the 80 V source and the power dissipated in the 8 Ω resistor using the mesh-current method.
ECE 201 Circuit Theory I

3. Identify the mesh currents
ECE 201 Circuit Theory I

4. Assign the voltage polarities+ - I3 - + - + + - + - - + + I2 I1 - - +
ECE 201 Circuit Theory I

5. Write the mesh-current equations (1)+ - I3 - + - + + - + - - + + I2 I1 - - +
80 = 31I1 - 26I2 - 5I3
ECE 201 Circuit Theory I

6. Write the mesh-current equations (2)+ - I3 - + - + + - + - - + + I2 I1 - - +
80 = 31I1 - 26I2 - 5I3
0 = -26I1 +124I2 -90I3
ECE 201 Circuit Theory I

7. Write the mesh-current equations (3)+ -
0 = -5I1 -90I2 +125I3 I3 - + - + + - + - - + + I2 I1 - - +
80 = 31I1 - 26I2 - 5I3
0 = -26I1 +124I2 -90I3
ECE 201 Circuit Theory I

8. Write the equations in matrix form
ECE 201 Circuit Theory I

9. Check for off-diagonal symmetry
ECE 201 Circuit Theory I

10. Solving with TI-89 Check CATALOG for simult( --- press ENTER
[31,-26,-5;-26,124,-90;-5,-90,125],[80;0;0]) hit ENTER
Resulting column vector is
I1 = 5A
I2 = 2.5A
I3 = 2A
ECE 201 Circuit Theory I

11. Calculate the power delivered by the source
Psource = (Vsource)(I1) = (80V)(5A) = 400 W +
I1 = 5 A -
ECE 201 Circuit Theory I

12. Calculate the power dissipated in the 8Ω resistor
P8Ω = (I2)2R = (2.5)2(8) = 50 W
I2 = 2.5 A
ECE 201 Circuit Theory I