All Questions
92
questions
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Does a conducting rod moving in a magnetic field itself generate another magnetic field?
A standard problem in elementary EM goes something like this:
An infinite straight wire conducts a stationary current $I$. A conducting rod, perpendicular to the wire, moves with constant velocity ...
- 571
1
vote
1
answer
3k
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Deriving Ampere's law from Biot-Savart equation [closed]
As an exercise, I've been trying to derive Ampere's law from the Biot-Savart equation (in the static case). So basically I'm trying to prove:
\begin{equation}
\nabla \times \vec{B}(\vec{r}) = \mu_0\...
- 71
20
votes
3
answers
2k
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Electromagnetism problem: where does the magnetic field come from?
Consider the following problem:
Consider a plane with uniform charge density $\sigma$. Above the said plane, there is a system of conducting wires made up of an U-shaped circuit on which a linear ...
- 571
1
vote
1
answer
70
views
What $\oint\vec{B}\cdot d\vec{l}=51.5\mu T\cdot m$ mean?
I've been stuck on this practice exam question. I'm supposed to find current through a loop using Ampere's law. But instead of $\mu_0$ it says $\mu$ and it's made me very confused because I can't get ...
1
vote
1
answer
1k
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Why are Maxwell's equations not Galilean invariant? [closed]
So i am writing an essay on the conflict between galilean invarience and maxwell's electromagnetism. I am struggling to come up with 3 evidences that they conflict because I have a mediocre ...
1
vote
2
answers
277
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Problem understanding derivation of inhomogenous Maxwell's equation from its Lagrangian
I got this part from QFT Demystified when the author is trying to derive Maxwell's equation from its Lagrangian density $\mathcal{L}=-\frac{1}{4}F_{\mu\nu}F^{\mu\nu}-J^\mu A_\mu$. In this part, in ...
- 700
2
votes
1
answer
380
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A question on Andrew Strominger's lecture
(I now use the same conventions)
(I think the notations are clear enough if you are familiar with differential geometry. Further, I tagged this post as homework-and-excercises. What is the problem ...
- 3,691
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votes
2
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533
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Is curl of a vector a scalar quantity in 2 spatial dimensions? If it is so, then somebody help me understanding Maxwell's equations in 2+1 D
I have seen on wikipedia that in 2 spatial dimensions, Green's theorem, Gauss's divergence and Stokes theorems are equivalent and it makes sense. When I tried to write Maxwell's equations in 2+1 ...
- 77
0
votes
1
answer
2k
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Deriving Maxwell Equations in their covariant form
Mawell Equations, in a particular unit system, are:
\begin{eqnarray}
\nabla \cdot \vec{E} &=& \rho &(1)\\
\nabla \times \vec{B} &=& \frac{\partial \vec{E}}{\partial t} + \vec{J}&...
0
votes
1
answer
78
views
Fourier integral for field propagation
I am trying to calculate the pulse propagation in a linear medium, and I am having difficulty some calculation involve in Fourier transformation.
For example of the first order approximation of ...
- 195
1
vote
1
answer
248
views
Derive the form of the fields for TEM waves in a waveguide
In my book it says that for TEM waves in a waveguide, with: $$\textbf E = \textbf E_0(x,y)e^{i(kz-\omega t)}$$ and $$\textbf H = \textbf H_0(x,y)e^{i(kz-\omega t)},$$ where $z$ is the direction of the ...
- 789
0
votes
2
answers
2k
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Maxwell's equations for electromagnetic wave
Good day, I am a student of Physics at the university of Padova, I must solve this problem for my exam of electromagnetic fields, but I have got different problems. The text is the follower:
The ...
- 3
1
vote
1
answer
759
views
contravariant components of electromagnetic field tensor under lorentz transformation
I have to show, how the contravariant components of the electromagnetic field tensor behave under Lorentz transformation.
I guess the answer should look something like this
$$F'^{\mu\nu}=\frac{\...
- 562
1
vote
1
answer
130
views
Divergence of a specific electrical field [closed]
I need to show that the divergence of the electrical field given as
$$\vec{E}=\vec{e_{\theta}}\frac{A\sin\theta}{r}\exp[i\omega(t-r/c)]$$
is zero. As the vector (in sperical coordinates) containes ...
- 11
1
vote
2
answers
438
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Maxwell equations in Special Relativity [closed]
I'm currently studying special relativity, and with it, tensor algebra. I have some difficulties in deriving a tensor differential relation involving the field tensor $F_{\mu\nu}$.
I have the Maxwell ...
- 55