Help starting two dimensional vector plot (meshgrid and quiver) problem

I'm trying to find the right way to set up this exercise but I'm still a very basic user and don't know much of the functions I should use.

"A coaxial cable has an inner conductor with radius a and is surrounded by a grounded thin conductive shell of radius b. Assume the surface charge density on the inner conductor is p. Make a two dimensional vector plot of the electric flux density D for the cross section of the coaxial cable. Use a meshgrid of 0.75mm with limits of -15cm<x<15cm. At each rdi point you should plot the vectors of the electric flux density using the quiver command."

Is there anyone able to make a bulletpoint list (variables and relative functions) I can follow to attempt a solution to the problem? Thanks!

Answer 1

[Cyrus Tirband]

• Use the maxwell equation to determine the D inside the cable. Hint: define gaussian surface which is a concentric cylinder with radius r, with
• Make a meshgrid of x and y with the required spacing with

[x,y] = meshgrid(-15:0.075:15);

• The electric flux density you find will be a function of x^2+y^2, and its direction will be with ϕbeing given by:

phi = atan2(y,x);

• Quiver takes 4 arguments: the x grid points, the y gridpoints, the x component, and the y component. Write your code to calculate the x component of D and the y component of D, noting that D is zero inside the inner conductor and outside the outer conductor.

Dx = ...
Dy = ...

• Finally, use quiver to generate the required plot

quiver(x,y,Dx,Dy)