Magnetic Field Contour: 0.2-1, -3 to 3

In summary, the conversation was about creating a contour of the magnitude of the magnetic field in and out of a wire using a Matlab program. The function used is |B| = r for -1≤r≤ 1 and |B| = 1/r for -3≤r≤-1 & 1≤r≤3. The desired contour is for |B| from 0.2 to 1 with steps of 0.2 and in Cartesian coordinates from -3 to 3. The provided solution involves creating a matrix to store the values of B within the desired range and then plotting the contour.
  • #1
omiros
30
0
Hello everyone,

I am struggling a bit with a Matlab program that I am writing. I am supposed to create a contour of the magnitude of the magnetic field, in and out of a wire. Basically the function is

|B| = r for -1≤r≤ 1 and |B| = 1/r for -3≤r≤-1 & 1≤r≤3
where r is the radius

However the contour that I have to plot is for |B| from 0.2 to 1 with steps of 0.2 (0.2, 0.4, 0.6, 0.8, 1.0) and it also has to be in Cartesian coordinates x,y both from -3 to 3.

What I've gotten so far is :

[phii,rhoi]=meshgrid(-pi:0.05*pi:pi,-1:0.05:1);
[x,y]=pol2cart(phii,rhoi);
B1 = sqrt(x.^2+y.^2);
(for inside the wire)

rhoo=[-3:0.1:-1,1:0.1:3];
phio=[-pi:0.05*pi:pi];
[phio,rhoo]=meshgrid(phio,rhoo);
[x1,y1]=pol2cart(phio,rhoo);
B2 = 1./(sqrt((x1).^2+(y1).^2));
(outside the wire)

figure(3);
hold all;
contour(x,y,B1);
contour(x1,y1,B2);
hold off;

In conclusion my problem is how to limit both B1 and B2 for value only equals to the ones above.
 
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  • #2
Thank you for your help!</code>Here is the solution I got:[phii,rhoi]=meshgrid(-pi:0.05*pi:pi,-1:0.05:1);[x,y]=pol2cart(phii,rhoi);B1 = sqrt(x.^2+y.^2);rhoo=[-3:0.1:-1,1:0.1:3];phio=[-pi:0.05*pi:pi];[phio,rhoo]=meshgrid(phio,rhoo);[x1,y1]=pol2cart(phio,rhoo);B2 = 1./(sqrt((x1).^2+(y1).^2));%create a matrix to store the values of B that are within the rangeB1_matrix = zeros(size(B1));B2_matrix = zeros(size(B2));for i=1:length(B1) for j=1:length(B1) if B1(i,j) >= 0.2 && B1(i,j) <= 1 B1_matrix(i,j) = B1(i,j); end endendfor i=1:length(B2) for j=1:length(B2) if B2(i,j) >= 0.2 && B2(i,j) <= 1 B2_matrix(i,j) = B2(i,j); end endendfigure(3);hold all;contour(x,y,B1_matrix);contour(x1,y1,B2_matrix);hold off;
 

1. What is a magnetic field contour?

A magnetic field contour is a representation of the strength and direction of a magnetic field at different points in space.

2. What does the range 0.2-1 indicate in the magnetic field contour?

The range 0.2-1 indicates the strength of the magnetic field, with 0.2 being the weakest and 1 being the strongest. This range is typically measured in units of Tesla (T).

3. What does the range -3 to 3 indicate in the magnetic field contour?

The range -3 to 3 indicates the direction of the magnetic field, with negative values indicating a southward direction and positive values indicating a northward direction.

4. How is a magnetic field contour created?

A magnetic field contour is created by plotting data points of the magnetic field strength and direction at different locations and connecting them with lines to create a visual representation.

5. What can a magnetic field contour tell us?

A magnetic field contour can tell us about the strength and direction of a magnetic field at different points in space, which can be useful in understanding the behavior of magnetic fields and their effects on objects and particles in their vicinity.

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