All Questions
Tagged with electromagnetism charge
666 questions
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If a large enough electron beam accelerates enough, will its induced electric fields, stop it?
Given acceleration of a beam of charges, there should exist a changing magnetic field around a beam of charges. That changing magnetic field is equal to the negative curl of the induced electric field....
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Why does a constant vector potential along a circular direction have this form? [closed]
My question comes from page 202 in the book "String theory and M-theory" by Becker-Becker-Schwarz. In Exercise 6.2 in this page, the author says:
"Consider a relativistic point ...
- 834
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System symmetries and electric field direction [closed]
I am a physics student. I am currently taking an introduction to electromagnetism. I would like to understand more rigorously the connection between system symmetries and (in this case) electric field ...
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Electrostatic generator,why they don't exist? [closed]
Suppose we have a two metallic plates separated by a dialectric medium inside a changing electric field.This according to Maxwell's equations will generate a electric current as opposed to generators ...
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Can a high enough charge density alone lead to the formation of a black hole?
Is there a fundamental upper limit to electric charge density?
If not, is it possible to concentrate enough charge in a small region of space such that an electron wouldn't be able to escape unless ...
- 732
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Charge induced inside a spherical conductor with a patch removed [closed]
When solving some problems meant for high school students, I came across this
A thin conducting shell of radius $R$ has surface charge density $\sigma$. A small aperture is made by removing a ...
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Increase in potential value due to a moving charge
We know that the charge density for a moving charge is taken as,
$$\rho(\mathbf{r}, t) = q \delta(\mathbf{r} - \mathbf{r}_q(t_r)).$$
This gives us the retarded potential of $$\phi(\mathbf{r}, t) = \...
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Expanding charged spherical cloud in vacuum
A spherical cloud charged uniformly (at $t=0$) with a total charge $Q>0$ will expand due to the electric repulsion. We assume we are in vacuum, so $\varepsilon=\varepsilon_0$. I'm trying to solve ...
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Dynamic $E$ field line angle with respect to charged surface
Imagine a situation. There is a large conducting plate that is much longer than it is wide. Then there is a small plate , both are charged, the small plate is moved around keeping the separation ...
- 101
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How does rubbing and friction increase triboelectric charge?
When two objects are placed in contact, a redistribution of charges occurs. This is due to their sharing of electrons, which gives one object a negative and another a positive charge. This specific ...
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Value of epsilon in the relaxation time for metals
I have found a series of related questions regarding the relaxation time $\tau$ for good conductors, however only a few briefly cited the assumptions on the value of $\epsilon$ when calculating $\tau$....
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How can point particles be Lorentz Contracted?
We know that single electrons undergo Lorentz contraction as their fields change in different frames as if a spherical distribution of charge was contracted to be an ellipsoid. However, since ...
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Why was the ampere redefined in 2019?
Before 2019, the ampere was essentially defined by fixing the vacuum permeability $\mu_0$ to be $4\pi\times10^{-7} \frac{H}{m}$. From 2019 onwards, the ampere was essentially defined by fixing the ...
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Which equation does $j=ρv$ refer to?
I found this statement in my physics book, however I am unable to recall/ understand which equation this is, moreover the variables are not defined (I don't know what $v$ refers to). The relation $j=...
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How to tell if a charge is accelerating due to gravity or electric field?
Picture yourself floating in deep space. Suppose you observe a charged particle with non-negligible mass accelerating. I wonder if there is a sure-fire way to tell if the charge is accelerating due to ...
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