Resistive Network Examples

Contents

Example 1

R = [20 40 20];
V = [10 0  5];
G = sum(1./R);
B = sum(V./R);
vx = B/G;
fprintf('Node voltage analysis\n');
fprintf('Vx = %g V\n',vx);
fprintf('current through R1 %g mA\n',(V(1)-vx)/R(1)*1000);
fprintf('current through R2 %g mA\n',vx/R(2)*1000);
fprintf('current through R3 %g mA\n',(V(3)-vx)/R(3)*1000);

% Notice that the circuit _supplies_ power to V3 (like a battery charger)

fprintf('Mesh current analysis\n');
A = [ R(1)+R(2) R(2); R(2) R(2)+R(3)];
B = [ V(1); V(3) ];
I = A\B;
fprintf('current I1 %g mA\n',I(1)*1000);
fprintf('current I2 %g mA\n',I(2)*1000);

Node voltage analysis
Vx = 6 V
current through R1 200 mA
current through R2 150 mA
current through R3 -50 mA
Mesh current analysis
current I1 200 mA
current I2 -50 mA

Example 2

using resistances in k Ohm and current in mA gives voltage in Volts (V = IR)

R = [1 2 10 2];
I = [10 50];
G = [ sum(1./R(1:3)) -sum(1./R(2:3)); -sum(1./R(2:3)) sum(1./R(2:4))]
B = [ I(1); -I(2)]
V = G\B

G =

    1.6000   -0.6000
   -0.6000    1.1000


B =

    10
   -50


V =

  -13.5714
  -52.8571

Example 3

R = [5 10 5 5];
V = [10 9 1];
A = [R(1)+R(2) -R(2); -R(2) R(2)+R(3)+R(4)]
B = [V(1)-V(2); V(2)-V(3)]
I = A\B

A =

    15   -10
   -10    20


B =

     1
     8


I =

    0.5000
    0.6500

Example 4

R = [3 8 6 4];
V = [12 6];
A = [R(1)+R(2) -R(2) -R(1); -R(2) R(2)+R(3) -R(3);
    -R(1) -R(3) R(1)+R(3)+R(4)]
B = [V(1); V(2); 0];
I = A\B

A =

    11    -8    -3
    -8    14    -6
    -3    -6    13


I =

    6.9000
    6.3000
    4.5000

Published with MATLAB® 7.4