All Questions
Tagged with conservation-laws charge
95
questions
-1
votes
2
answers
93
views
Charge conservation in ohmic material - Apparent paradox
Consider an ohmic material with constant conductivity, which obeys the relation:
$$\vec J = \sigma \vec E$$
where $\vec J$ is the current density and $\sigma$ is the conductivity. Applying the first ...
- 1,616
1
vote
2
answers
138
views
Electrons repel each other forever - why? [closed]
I.e. charge is conserved.
How? Why?
Background
I am coming here with only my intuition, and a desire to learn. My intuition "feels" that if an electron keeps on repelling other electrons, ...
- 149
0
votes
1
answer
61
views
What is the mechanism that generates equal numbers of protons and electrons in our universe?
As far as we know the universe is electrically neutral. An electron-positron pair is easy to create. It is not related to the creation of quarks. So why are there the same number of electrons and ...
- 1,045
1
vote
0
answers
33
views
Charge conservation and $U(1)$-invariance [duplicate]
Let’s consider electromagnetic Lagrangian
$$\mathcal L=-{1\over 4}F_{\mu\nu}F^{\mu\nu}\tag{1}$$
Is charge conservation derived as a consequence of $U(1)$-invariance of this Lagrangian?
user394668
2
votes
3
answers
205
views
Deriving continuity equation from 4-current of a charged particle
how can i check that following 4-current for a single charged particle
$$j^{\mu}(x)=qc\int d\tau u^{\mu}(\tau)\delta^{4}(x-r(\tau))$$
satisfies continuity equation $$\partial_\mu j^\mu = 0.$$
user391340
0
votes
1
answer
90
views
How to determine the charge of a $W$ boson in a Feynman diagram?
As the title says, I am not sure in what situations there is a W$^+$ boson and when there is a W$^-$ boson. My lecturer explained to me that you can view it either as the $W$ boson supplying a charge ...
- 1
4
votes
1
answer
610
views
How is Law of Conservation of Charge valid if protons and electrons are destroyed in a system?
So I am preparing for an exam with material from openstax books on physics. There in the static electricity chapter I saw this paragraph,
"Because the fundamental positive and negative units of ...
- 53
2
votes
2
answers
188
views
Total bound charge equal to zero (proof)
I always see the assumption that the total bound charge is always zero, but is it not clear for me why is it true for every dielectric material, and I haven't find it in a textbook.
I know that $\...
1
vote
3
answers
105
views
Electric field of an electron after it comes into existence
This is a followup of an older post I made here, whose main premise was not answered. Suppose than an electron is created in a scattering experiment, where other particles are created/destroyed in ...
- 167
-2
votes
1
answer
91
views
How can charge be conserved when mass isn't? [duplicate]
If mass (consisting of protons and electrons) can be converted to energy by running it at the speed of light, wouldn't that also convert charge as charge is due to and quantized over electrons?
For ...
- 9
0
votes
2
answers
80
views
Kirchoff's Current Law - Confusion
While I come across some explanations on why KCL works, it is usually attributed to the Law of Conservation of Charge. But by the statement of KCL, it states that the current entering and leaving a ...
1
vote
2
answers
171
views
Is the continuity equation used to **define** the current density?
Recall the continuity equation:
$$\frac{\partial}{\partial t}\rho+\boldsymbol{\nabla\cdot J}=0$$
Given $\rho$, there is obviously not a unique solution $\boldsymbol{J}$, but I guess one could choose ...
- 1,801
1
vote
1
answer
154
views
A calculation about Stoke's Formula in General Relativity
This is from the book by Carroll
the equations are $$Q=-\int _{\Sigma}d^3x\sqrt{\gamma} n_{\mu}J^{\mu}_{e
} =-\int _{\Sigma}d^3x\sqrt{\gamma} n_{\mu} \nabla_{\nu} F^{\mu\nu}$$
$$Q=-\int _{\partial\...
- 41
3
votes
1
answer
237
views
How does a charge or a Noether charge create a continuous symmetry?
I recently searched up the definition for a more generalized definition of charge whether it be color charge or electric charge . And I found this but i fail to understand what this statement actually ...
- 159
-1
votes
2
answers
103
views
Local conservation of charge does not imply global conservation of charge?
In order for a set of $\rho, \vec{J}$ functions to conserve charge locally.
$$\nabla \cdot \vec{J} = - \frac{\partial \rho}{\partial t}$$
Consider
$$\vec{J} = x \hat i$$
Does this have a valid ...
- 6,636