All Questions
70
questions
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233
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Electric field evaluation in electrostatics and electrodynamics
it is known that an electrostatic field may be expressed in the following way (where r expresses the position of observation):
$E(r) = -\nabla \Phi(r)$
where $\Phi$ is the electrostatic potential. ...
- 1,319
1
vote
1
answer
79
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Point charge potential and electric field [closed]
What is the difference between the 2D and 3D electric field and the potential. Why is it that the potential increases when going from the 2D to the 3D representation but the electric field decreases? ...
- 97
7
votes
3
answers
346
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Why do clothes produce sounds after being in front of a computer for a long time?
Quite often, after sitting in front of the computer not moving a whole lot for a long time my upper body clothes (usually sweaters) make soft crackling sounds when moving or specially when taking them ...
- 171
0
votes
0
answers
341
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Electric field on the surface of dielectric sphere and outside sphere
Let a dielectric sphere of radius $r_0$ and permittivity $\epsilon_1$ is placed in medium of permittivity $\epsilon_2$. The electric field inside sphere is $\mathbf{E_1(\mathbf{r})} = E_0 \hat{z}$. ...
- 1,335
1
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0
answers
34
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creating a varying electric field across a copper strip
Hi I am trying to create a varying electric field (by position on copper strip) across a copper strip by attempting a standing wave pattern. the following is a diagram
may I have some guidance on how ...
- 111
1
vote
0
answers
230
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Retarded Coulomb's law and EM waves; Feynman texts
In this chapter, Feynman writes down the retarded Coulomb's law,
$$\begin{equation}
\label{Eq:II:21:1}
\mathbf E=\frac{q}{4\pi\epsilon_0}\biggl[
\frac{\mathbf e_{r'}}{r'^2}+\frac{r'}{c}\,\frac{d}{dt}\...
- 455
2
votes
0
answers
70
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A travelling field; Feynman lectures on Physics Volume 2
In Feynman's Lectures on Physics, volume 2, Chapter 18 (18-5), we look at the creation of a electromagnetic field, due to a moving infinite sheet of charge,
By looking at the Maxwell equations ...
- 455
1
vote
1
answer
697
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Electric Field inside an ideal conductor
I have some doubts about the electric field inside an ideal conductor (let's call it E). Precisely, I have read two different descriptions
1) On physics books I read that the electric field inside in ...
- 1,319
0
votes
1
answer
371
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Electric field from the intersection of two spheres with different charges
This question is repeated a lot, but I for two spheres with different charge densities, sphere one with radius a centered at the origin and charge density $\rho_1$, and sphere two with radius centered ...
- 111
1
vote
2
answers
219
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What is the relation between the frequency of the light produced and the acceleration of the charged particle
We know that accelerating charges produce EM radiation. Can we derive a relation between frequency of the light produced and the accelaration of the charge ?
0
votes
2
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944
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Expressing Maxwell's equations as scalar equations involving differentials in Euclidean space
I am trying to convert Maxwell's equations from the well known differential form (found on Wikipedia Maxwell's equations) into scalar equations involving partial derivatives (more than four equations)....
- 469
1
vote
2
answers
539
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inverse square law and far-field radiation
This question is related to Feynman on inverse square law of EM radiation.
It is basicly the same question except that I don't see that the question was ever answered, and I hope someone will answer ...
- 2,988
0
votes
1
answer
32
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What are the magnitude of voltage fluctuations in field surrounding the human head?
How much would the scale of the electric field caused by neuron activity in the brain vary as it radiated from the scalp? Also what would be the typical noise level over the same space attributable to ...
- 1,144
1
vote
0
answers
126
views
Why is electric dipole moment represented by "p"?
I recently came across a text where the electric dipole moment was represented as "d" instead of the more commonly used "p". The reason behind using "d" here is probably that "dipole moment" begins ...
- 21
1
vote
1
answer
241
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Electric force between two parallel plates one of which got a rough surface
So if I have two parallel metal sheets separated by 0.1 meters with air as a dielectric with a breakdown strength of 3MV/m and I'm applying a voltage pulse that goes from 0 to 100kV in few ...
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