Contents

Question 1

For the following circuit, find (a) the value of the current I, (b) the value of the voltage across each resistor, and (c) the power absorbed or produced in each element.

% Initial Information
R1 = 400;
R2 = 180;
R3 = 620;
Vi = 12;

% a - the value of the current I
I = Vi/(R1+R2+R3);
fprintf('a) Current I: %g\n',I);

% b - the value of the voltage across each resistor
V1 = I*R1;
V2 = I*R2;
V3 = I*R3;
fprintf('b) Voltage across Resistor 1: %g\n',V1);
fprintf('   Voltage across Resistor 2: %g\n',V2);
fprintf('   Voltage across Resistor 3: %g\n',V3);

% c - the power absorbed or produced by each element
P1 = (I^2)*R1;
P2 = (I^2)*R2;
P3 = (I^2)*R3;

fprintf('c) Power absorbed by R1: %g\n',P1);
fprintf('   Power absorbed by R2: %g\n',P2);
fprintf('   Power absorbed by R3: %g\n',P3);

a) Current I: 0.01
b) Voltage across Resistor 1: 4
   Voltage across Resistor 2: 1.8
   Voltage across Resistor 3: 6.2
c) Power absorbed by R1: 0.04
   Power absorbed by R2: 0.018
   Power absorbed by R3: 0.062

Question 2

Find the value of the current I flowing into the node.

% Initial Information (positive means going into the node, negative leaving
% the node)
I1 = -60;
I2 = 140;
I3 = -30;

% Value of current I
I = -1*(I1+I2+I3);
fprintf('Value of current I: %g\n',I);

Value of current I: -50

Question 3

Determine the current flowing through and the voltage across each resistor in the following circuit. Also determine the equivalent resistance of the circuit.

% Initial Information
Vi = 48;
R1 = 100;
R2a = 480;
R2b = 480;
R2c = 480;
R3a = 50;
R3b = 200;

% Equivalent resistance of parallel resistors:
R2 = (1/R2a)+(1/R2b)+(1/R2c);
R2 = 1/R2;
R3 = (1/R3a)+(1/R3b);
R3 = 1/R3;

% Value of Current I:
I = Vi/(R1+R2+R3);

% Resistor 1:
% Current flowing through:
I1 = I;
% Voltage across:
V1 = I1*R1;
fprintf('R1 - Current: %g\n',I1);
fprintf('R1 - Voltage: %g\n',V1);

% Resistors 2:
% Current flowing through:
I2a = (Vi-V1)/(R2a);
I2b = (Vi-V1)/(R2b);
I2c = (Vi-V1)/(R2c);
% Voltage across:
I2 = I;
V2 = I2*R2;
V2a = V2;
V2b = V2;
V2c = V2;
fprintf('R2a - Current: %g\n',I2a);
fprintf('R2a - Voltage: %g\n',V2a);
fprintf('R2b - Current: %g\n',I2b);
fprintf('R2b - Voltage: %g\n',V2b);
fprintf('R2c - Current: %g\n',I2c);
fprintf('R2c - Voltage: %g\n',V2c);

% Resistors 3:
% Current flowing through:
I3a = (Vi-V1-V2)/(R3a);
I3b = (Vi-V1-V2)/(R3b);
% Voltage across:
I3 = I;
V3 = I3*R3;
V3a = V3;
V3b = V3;
fprintf('R3a - Current: %g\n',I3a);
fprintf('R3a - Voltage: %g\n',V3a);
fprintf('R3b - Current: %g\n',I3b);
fprintf('R3b - Voltage: %g\n',V3b);

%Equivalent Resistance:
Rs = R1+R2+R3;
fprintf('Equivalent Resistance: %g\n',Rs);

R1 - Current: 0.16
R1 - Voltage: 16
R2a - Current: 0.0666667
R2a - Voltage: 25.6
R2b - Current: 0.0666667
R2b - Voltage: 25.6
R2c - Current: 0.0666667
R2c - Voltage: 25.6
R3a - Current: 0.128
R3a - Voltage: 6.4
R3b - Current: 0.032
R3b - Voltage: 6.4
Equivalent Resistance: 300

Published with MATLAB® 7.4