Determining electric field from electrostatic potential

I am trying to determine Elecric field from 2D electrostatic potential. E = -grad (V); I have a 2D matrix of (V). When I am writing [Ex Ey]=-imgradient(V,'sobel') I am getting error as Error using '-' , too many arguments. Someone kindly help to correct it.

Answer 1

[nick]

Hi Somnath,

I noticed an issue in the code regarding the use of the '-' operator with the 'imgradient' function in MATLAB. To ensure correct functionality, the code should be adjusted as follows:

[Ex Ey]=-1*imgradient(V,'sobel')

You may refer to the following documentation to learn more about operators in MATLAB :

https://www.mathworks.com/help/matlab/matlab_prog/matlab-operators-and-special-characters.html

Hope this helps!

[Somnath]

Thank you for your reply. I have tried it but it is still giving the same error message.

[nick]

Hi Somnath,

Thanks for letting me know about the persistent error. I apologize the inconvenience it may have caused. You can instead of compute gradient of '-1*V' instesad of 'V' to resolve the error.

The 'imgradient' function is primarily used for image processing, as it returns the gradient magnitude of a 2-D image.

To determine the 2-D Electric field frim potential, V, you can instead use the fucntion 'gradient'. The function returns the N components of the gradient of F, where F is an array with N dimensions. Here's an example MATLAB script of the same:

V = rand(5, 5); % Example 2D potential matrix

% Calculate the gradient of V
[Ex, Ey] =  gradient(-1*V);

% Display the results
figure;
quiver(Ex, Ey);
title('Electric Field from Potential');
xlabel('X-axis');
ylabel('Y-axis');
axis equal;

You can refer to the following documentations to learn more about 'imgraident' and 'gradient':

imgradient: https://www.mathworks.com/help/releases/R2024a/images/ref/imgradient.html

gradient: https://www.mathworks.com/help/matlab/ref/gradient.html

I hope this helps, and feel free to reach out if you have any more questions!

[Somnath]

Thank you very much.

Answer 2

[Shivam]

Hi Somnath,

I see that you are encountring the error while calculating electric field from 2D electric potential.

In vector calculus notation, the electric field is given by the negative of the gradient of the electric potential, E = −grad V.

You can follow the below workaround to correctly calculate the Electric Field:

% Compute the gradient components
[Ex, Ey] = imgradient(V);

% The electric field is the negative gradient of the potential
Ex = -Ex;
Ey = -Ey;

I hope this resolves the issue.

Regards,

Shivam

[Somnath]

Thank you very much.

Answer 3

[Eliezer]

See more here:

Campo Elétrico