Tagged Questions
1
vote
2answers
118 views
Lorenz gauge fixing
Is it always possible to define function $\psi$ satisfying the Lorenz gauge equation
$$
\partial_{\mu}\partial^{\mu} \psi + \partial_{\mu}A^{\mu} = 0?
$$
2
votes
2answers
279 views
Higher To Lower Electric Potential
The question I am working on is:
"An electron moving parallel to the x axis has an initial speed of $4.65 \cdot 10^6~m/s$ at the origin. Its speed is reduced to $1.27 \cdot 10^5 ~m/s$ at the point ...
4
votes
1answer
126 views
Kaluza-Klein Christoffel Symbols
I have a question regarding the connection coefficients as they pertain to the following paper: http://www.weylmann.com/kaluza.pdf . When I try to calculate the 4D Christoffel symbols from the 4D part ...
4
votes
1answer
276 views
How to interpret the magnetic vector potential?
In electromagnetism, we can re-write the electric field in terms of the electric scalar potential, and the magnetic vector potential. That is:
$E = -\nabla\phi - \frac{\partial A}{\partial t}$, ...
1
vote
2answers
264 views
Vector Potential and Gauge Invariance in Quantum Mechanics
In classical electromagnetism, we are allowed to use gauge invariance through the argument that the only physical observable fields are the $E$-field and the $B$-field. So in that sense the scalar ...
0
votes
1answer
89 views
Is it possible to charge a capacitor to any potential? Does it depend on the dielectric placed between them?
Is it possible to charge a capacitor to any potential? Does it depend on the dielectric placed between them? Or, are there other factors affecting it?
4
votes
1answer
111 views
Linear dependence of magnetic potential on current density
I'm a mathematician learning physics to provide some background for my mathematical work (especially pde's!). I have been reading through Jackson's Classical Electrodynamics (3rd edition), and I was ...
0
votes
1answer
387 views
Maxwell's Correction to Ampere's Law
I have not yet officially studied Electromagnetism but am trying to teach myself at the moment. I understand Maxwell's equations in the context of Magneto- and Electrostatics: they are equivalent, ...
1
vote
3answers
3k views
How is calculated the potential between two capacitors in series?
Suppose to have two capacitors in series:
The voltage in the middle point will be:
$$
V_X = V_1 \frac{C_1}{C_1+C_2}
$$
How can this be explained? It's been asked in electronics, and explained in ...
0
votes
1answer
314 views
Potential difference between conductors
Reading some books there is something that i don't understand. Is the capacitors topics when they name a potential difference between conductors.
As i know, Potential difference is the difference in ...
1
vote
0answers
93 views
An electron is subjected to an electromagnetic field using the canonical equations solve
So I was given the following vector field:
$\vec{A}(t)=\{A_{0x}cos(\omega t + \phi_x), A_{0y}cos(\omega t + \phi_y), A_{0z}cos(\omega t + \phi_z)\}$
Where the amplitudes $A_{0i}$ and phase shifts ...
4
votes
1answer
121 views
Loopless voltage measurement
I think we are all very well familiarized with the classical voltmeter. Classical voltmeter has two conducting wires that bring two potentials into the box. In the box we have well controlled ...
1
vote
2answers
90 views
Origin of field deduced from potential
Related: Tubelights+power lines pictures?
I would've edited this into the above question, but I realized that there' enough to it to qualify as a new one. Plus this seems to be a confusion of ...
1
vote
1answer
75 views
Formula for potential for 2 coaxial tubes
Could someone remind me of the formula for potential function for a system consisting of 2 coaxial tubes maintained at a fixed potential difference and the in between medium has uniform conductivity ...
1
vote
2answers
442 views
Image charges, laplace equation and uniqueness theorem
Consider a well-known problem of the electric field generated by a system composed of a point charge in proximity of a large earthed conductor. It is said that the potential due to an image charge ...
0
votes
1answer
55 views
Potential at a point
What is the electric dipole moment of the charge distribution with $q$ at $(0,0,1)$, $q$ at $(0,0,-1)$ and $-2q$ at $(0,0,0)$? I would think that it is $\vec{0}$ by the definition ...
1
vote
1answer
144 views
Complex Potentials, Potentials and Fields
Suppose an electric field $E=-\nabla \psi$ where $\psi=-Q\ln r$ where $Q$ is just some constant and I have found its harmonic conjugate to be $-Q\theta+c$ where $c$ is some constant. What does it say ...
0
votes
2answers
656 views
How to calculate the electric field at a point in space
Let's say I have a uniformly-charged wire bent into a semi-circle around the origin. How can I find the electric field (magnitude and direction)
I'm not even sure if I should use Coulomb's or Gauss' ...
1
vote
2answers
589 views
If electric charges accelerate towards lower potential energies, why do opposite charges attract?
I know my logic must be wrong but I can't figure out why. I know that charges must accelerate towards lower potential energies simply because that's a general rule of nature. However, when you release ...
9
votes
2answers
216 views
Motivation for Potentials
This is a hypothetical question about "pedagogy". Let's say I am trying to take someone who has just a very small amount of knowledge about Newtonian mechanics and convince them that the Lagrangian ...
8
votes
8answers
3k views
What is the difference between electric potential, voltage and electromotive force?
This is a confused part ever since I started learning electricity. What is the difference between voltage and electromotive force (emf)? Both of them have the same SI unit, right? I would appreciate ...
