Maxwell equations in terms of potentials

In summary, the Maxwell equations in potential formulation can be simplified and generalized to D-dimensional space by using the electromagnetic tensor and replacing vector operators with partial derivatives and sums. The equations should not contain vector products on operators, but instead utilize the Levi-Civita symbol and other tensor formulations. The correct equation system in D dimensions would be: ∇2φ = DIV(grad(φ)) . Am I right?Yes∇2A = ROT(ROT(A))=ROT(B)=grad(DIV(A))-Laplace(A) . Am I right?No. The correct equation is: ∇2A = DIV(ROT(A))=DIV(B)=grad(DIV(A))-Laplace(A)In coulomb gauge in
  • #1
olgerm
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These are Maxwell´s equations in potential formulation:
29ed508c553583e1477fc6a3681158fe.png

621ac837ee1d1d742fcf5ed3f73c033a.png


2φ = DIV(grad(φ)) . Am I right?
2A = ROT(ROT(A))=ROT(B)=grad(DIV(A))-Laplace(A) . Am I right?
In coulomb gauge in every point and at any time DIV(A)=[PLAIN]https://upload.wikimedia.org/math/4/4/1/44131cc26bd9db464d0edb7459ccca84.png. Am I right?
Where could I find Maxwell´s equations in terms of potentials without vector operator?

How must ROT (same as curl) be generalized to make the equations describe EM-field in D-dimensional space equally with these equation
##\begin{cases}
& \sum_{i=1}^D(\frac{\partial E_i}{\partial x_i})=\rho \frac{1}{{\epsilon_0}} \\
& \frac{\partial E_a}{\partial t}=\sum_{i=1}^D(\frac{\partial B_{[i;a]}}{\partial x_i})-J_a \\
& \frac{\partial B_{[a;b]}}{\partial t}=\frac{\partial E_b}{\partial x_a}-\frac{\partial E_a}{\partial x_b}\\
& \frac{\partial B_{[a;b]}}{\partial x_c}+\frac{\partial B_{[b;c]}}{\partial x_a}+\frac{\partial B_{[c;a]}}{\partial x_b}=0
\end{cases}##
,which are in terms of E and B?

φ is electripotentialfield.
E is electricvectorfield.
A is magneticpotentialvectorfield.
B is magneticvectorfield.
ρ is electriccharge density.
 
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  • #2
olgerm said:
∇2φ = DIV(grad(φ)) . Am I right?
Yes
olgerm said:
∇2A = ROT(ROT(A))=ROT(B)=grad(DIV(A))-Laplace(A) . Am I right?
No. Look here: https://en.wikipedia.org/wiki/Vector_Laplacian
olgerm said:
In coulomb gauge in every point and at any time DIV(A)=
p?image=https%3A%2F%2Fupload.wikimedia.org%2Fmath%2F4%2F4%2F1%2F44131cc26bd9db464d0edb7459ccca84.png
. Am I right?
Yes
olgerm said:
Where could I find Maxwell´s equations in terms of potentials without vector operator?
You can do this yourself. Just take what you have above and replace with partial derivatives. Also, this might be useful
https://en.wikipedia.org/wiki/Covariant_formulation_of_classical_electromagnetism

Your last question is a little weird. Are interested in a 2D subset (x,y) of 3D space (x,y,z) where z is a symmetry?
 
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  • #3
Khashishi said:
It seems to confirm, that ROT(ROT(A))=grad(DIV(A))-Laplace(A) .
also this http://m.wolframalpha.com/input/?i=curl+(curl+A)&x=0&y=0 seems to confirm, that ROT(ROT(A))=grad(DIV(A))-Laplace(A) . Or does ∇2 A in the second equation note Laplace(A) not ROT(ROT(A))?

Khashishi said:
Your last question is a little weird. Are interested in a 2D subset (x,y) of 3D space (x,y,z) where z is a symmetry?
I am interested about theoretical physical system with D-dimensional space. Understanding physical meaning of such system is not necessary to answer the question.
 
  • #4
##\nabla^2 A## means the same thing as Laplace(A).

How many dimensions do you want to work in?
 
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  • #5
Khashishi said:
How many dimensions do you want to work in?
D dimensions. Generalization must include variable D.
 
  • #6
Now as I understand there are different Laplacians for vectorfield and scalarfield it makes more sense.

So are these equations in lorenz gauge
##\begin{cases}
\frac{\partial^2 A_{D_1}}{\partial t^2}=J_{D_1}\cdot k_E \cdot \pi \cdot c^2 \cdot 4+\sum_{i=1}^D(\frac{\partial^2 A}{\partial x_i \cdot \partial x_{D_1}}) \cdot c^2-ROT(ROT(A)) \cdot c^2\\
\frac{\partial^2 \phi}{\partial t^2}=\rho \cdot k_E \cdot \pi \cdot 4+\sum_{i=1}^D(\frac{\partial^2 \phi}{\partial x_i^2})\\
\frac{\partial \phi}{\partial t}=\sum_{i=1}^D(\frac{\partial A_i}{\partial x_i}) \cdot c^2\\
F_E=q\cdot(\sum_{i=1}^D(v_i \cdot \frac{\partial A_i}{\partial x_{D_1}})-\frac{\partial A_{D_1}}{\partial t}-\frac{\partial \phi}{\partial x_{D_1}})
\end{cases}##
?

But what must ROT(ROT(A)) equal to in D-dimensional space so that the Maxwell equations were equal with these
##\begin{cases}
& \sum_{i=1}^D(\frac{\partial E_i}{\partial x_i})=\rho \frac{1}{{\epsilon_0}} \\
& \frac{\partial E_a}{\partial t}=\sum_{i=1}^D(\frac{\partial B_{[i;a]}}{\partial x_i})-J_a \\
& \frac{\partial B_{[a;b]}}{\partial t}=\frac{\partial E_b}{\partial x_a}-\frac{\partial E_a}{\partial x_b}\\
& \frac{\partial B_{[a;b]}}{\partial x_c}+\frac{\partial B_{[b;c]}}{\partial x_a}+\frac{\partial B_{[c;a]}}{\partial x_b}=0
\end{cases}##
equation?
I also want the equation system to be formed as short and easy as possible. What gauge you recommend me to choose? Any ideas how to simplify the equations?
 
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  • #7
I have hypothesis, that Laplace(A) must be generalized to be equal to ## 2\cdot\frac{\partial^2 A_{D_1}}{\partial x_{D_1}^2}-\sum_{i=1}^D(\frac{\partial^2 A_{D_1}}{\partial x_i^2})## .
Can anybody check if it is correct?
 
  • #8
You know what the electromagnetic tensor is? You should use a tensor formulation if you want to generalize to different dimensions. I asked what dimension you wanted to work in because it affects the answer. Cross product only really works in 3 or 7 dimensions. You might want to use the Levi-Civita symbol.
 
  • #9
Khashishi said:
You know what the electromagnetic tensor is? You should use a tensor formulation if you want to generalize to different dimensions.
I got the equations in E and B formulation from Maxwell equations in electromagnetic tensor formulation.

The equations should not contain vector products on operators, but partial derivatives and sums. D must be a variabe, that can be equal to any natural number.
 
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  • #10
I have got my answer. Correct equation system is:
##\begin{cases}
\frac{\partial^2 A_{D_1}}{\partial t^2}=J_{D_1}\cdot k_E \cdot \pi \cdot 4+\sum_{i=1}^D(\frac{\partial^2 A_{D_1}}{\partial x_i^2}) \cdot c^2\\
\frac{\partial^2 \phi}{\partial t^2}=\rho \cdot k_E \cdot c^2 \cdot \pi \cdot 4+\sum_{i=1}^D(\frac{\partial^2 \phi}{\partial x_i^2})\\
\frac{\partial \phi}{\partial t}=\sum_{i=1}^D(\frac{\partial A_i}{\partial x_i}) \cdot c^2\\
F_E=q\cdot(\sum_{i=1}^D(v_i \cdot \frac{\partial A_i}{\partial x_{D_1}})-\frac{\partial A_{D_1}}{\partial t}-\frac{\partial \phi}{\partial x_{D_1}})
\end{cases}##
 

Related to Maxwell equations in terms of potentials

1. What is the significance of using potentials in Maxwell's equations?

Potentials allow us to simplify and express Maxwell's equations in a more elegant and concise form. They also make it easier to solve certain problems in electromagnetism, such as those involving symmetries or boundary conditions.

2. What are the two types of potentials used in Maxwell's equations?

The two types of potentials are the scalar potential (ϕ) and the vector potential (A). These potentials are used to describe the electric and magnetic fields, respectively.

3. How are the scalar and vector potentials related to the electric and magnetic fields?

The electric field (E) is the negative gradient of the scalar potential (ϕ), while the magnetic field (B) is the curl of the vector potential (A). In other words, E = -∇ϕ and B = ∇ x A.

4. Can Maxwell's equations be expressed solely in terms of potentials?

Yes, it is possible to express Maxwell's equations solely in terms of potentials. This is known as the "potential formulation" of Maxwell's equations and is often used in theoretical and computational studies.

5. What are the benefits of using the potential formulation of Maxwell's equations?

The potential formulation allows for a more intuitive understanding of the underlying physics and can simplify the mathematical calculations. It also allows for the application of certain mathematical techniques, such as the method of images, to solve problems in electromagnetism.

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