Question

2- Write a MATLAB code to visualize (2D) the electric field vector due to four equal point charges Q, Placed at vertices of a rectangle of length a and width w in free space. The code must ask the user to input the value of the charge and the size of the edges.

Answer 1

%we can use this code to generate the vector plot

clear all;

clc;

close all;

%Single input : define the number of points

lamda = input('Enter the charge Density in Q/m:(example "5e-9" , which is 5nC)');

%

l = input('Enter the edge length of visulatiztion box centerd at wire,in meters (example "1" which is 1 meter:)'); %created a 2D mesh resolution = 0.1 ;% default of 0.1meters [x,y] = meshgrid(-1*l/2:resolution:l/2,-1*l/2:resolution:l/2) ;

eps0 = 8.854*1e-12;

%no create a 2D array with field flux values

% magnitude of electric field due to infinite line = lamda/(2*pi*r*eps0) ;

r = sqrt(x.^2+y.^2);

theta = ((atan(y./x)).(x>=0)) + ((pi+atan(y./x)).(x<0));

E = lamda./(2*pi.*r.*eps0) ;

%compute components Ex = E.*cos(theta); Ey = E.*sin(theta);

%plot the 2D flux of filed lines contour(x,y,E);

hold on;

quiver(x,y,Ex,Ey);

hold off;

grid on;

xlabel('x') ylabel('y') title('Electric field line vector plot ')

%*****

%sample run :

Enter the charge Density in Q/m:(example "5e-9" , which is 5nC)5e-9

Enter the edge length of visulatiztion box centerd at wire,in meters (example "1" which is 1 meter:)1

Electric field ine wector plot