All Questions
Tagged with linear-systems electromagnetism
27 questions
4
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1
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265
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Validity of linear superposition in solving Maxwell's equations
I'm currently reading the book "Electromagnetic Waves and Antennas" by S. J. Orfanidis (publicly available at his own website) and a doubt came to me.
I'm referring in particular to the ...
- 41
0
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0
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40
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Computing real part of AC conductivity via linear response theory
I am attempting to use linear response theory to compute the AC conductivity in fourier space.
Schematically, the AC conductivity $\sigma(\omega)$ is defined by
\begin{equation}
\langle J_i \...
- 3,926
2
votes
2
answers
202
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Understanding linearity of Maxwell's equation compared to non-linarity of GR
In this post, it is mentioned that a linear equation means that the solutions 'do not interact with each other' or 'do not know' about each other. But we know that Maxwell's equations are linear ...
- 879
1
vote
1
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94
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Complex representation of electric field
Hi I have been struggling for a while. Let's say I represent my complex field as $E_1=Ae^{i\omega t}$. Let's say this is the input to a component that takes in two inputs and is supposed to split the ...
- 21
1
vote
1
answer
80
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Confusion when utilizing complex electric field to do calculations
I've been struggling using complex exponentials. From my understanding using complex exponentials can simplify calculations without the use of sinusoidal waves. The thing that has been bothering me is ...
- 21
0
votes
0
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43
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How is complex number $i$ valid in phasors? [duplicate]
I get it that a a complex number has two components, one of which can be considered to be the value of the phasor and the angle can be considered the phase. Also, adding two phasors produces similar ...
- 1,312
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1
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110
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Do the solutions to Maxwell's equations form a group?
How many solutions are there for Maxwell's equations? (Or rather, is there a finite number of them?)
Regardless of how many solutions to these equations exist, could we claim they form a group? If so,...
- 2,164
0
votes
2
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84
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Possibility of complex EM waves
I'm currently studying Quantum Mechanics, and I have just been presented Schrödinger's (time dependent) equation. Of course, the first solution to said equation I've been taught is that of a (complex) ...
- 2,164
0
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1
answer
135
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Superposition of two electromagnetic waves
If an electromagnetic wave in isolation with vector potential $A^1_{\alpha}$ satisfies the wave equation $\Box A^1_{\alpha}=0$, how do we construct the total electromagnetic wave that results from ...
- 272
1
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0
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64
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The criteria for zero DC resistivity from Kramers-Kronig relation?
While studying introductory superconductor theory,
Neil Ashcroft came up with a criteria for zero DC resistivity as a following:
$$\lim_{w→0}w\cdot\rm{Im} \ \it{\sigma(w)}\neq\rm{0}$$
And this must ...
- 155
0
votes
1
answer
304
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Do retarded potentials imply homogenous solution?
I am having trouble reconciling the retarded potentials, with a possibility for a background homogenous solution to the EM field to exist.
In the Lorenz gauge $$\nabla \cdot \vec{A} = - \mu_0 \...
- 6,946
1
vote
1
answer
284
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How do I use dimensional analysis to find the ratio of potentials at the center and corner of a uniformly charged cube?
The problem goes like this, from Purcell's electromagnetism:
Consider a charge distribution that has the constant density $ρ$ everywhere inside a cube of edge $b$ and is zero everywhere outside that
...
- 595
2
votes
1
answer
496
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Complex physical quantities
I have a question regarding complex physical quantities. Why do we consider only the real part of a complex physical quantity? Why not the modulus?
Since, for $z=a+bi$, we have $|z| = \sqrt{a^2+b^2}$, ...
0
votes
3
answers
356
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Can superposition principle work with boundary conditions in electromagnetism?
Let's suppose I have two finite lines of charge, each of them at some voltage $V$. The first one would be at $x=0$ and the second one at $x=a$, and each of them has the same length $l$.
If I want to ...
- 13
19
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4
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In classical physics (classical electrodynamics), why linearity of Maxwell's equations prevent interaction of electromagnetic waves?
In classical physics (classical electrodynamics), electromagnetic waves don't interact. In quantum mechanics, they could. In this article on light-by-light scattering:
https://arxiv.org/abs/1702.01625
...
