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Questions tagged [potential]

Scalar and vector potentials in electromagnetism. The scalar potential is potential energy per unit charge. For potential energy, use the [potential-energy] tag.

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Difference Between Plasma Potential and Floating Potential in a Plasma

I'm learning about Langmuir probes and I'm confused about the difference between the plasma potential $V_p$ and the floating potential $V_f$. From my understanding, when a plasma is in contact with a ...
ReggiePlasmaQs's user avatar
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How Can there be a Gravitational Potential when there is NO Gravitational Field? [closed]

How does it make any logic that there exist a potential when there is no net field for example when we have a Hollow Sphere with mass we can find out the the gravitational *potential inside the sphere ...
Aditya Agrawal's user avatar
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Voltage: work to move a charge, or difference of electric potential?

Let's say I have a single positive charge inside of an electrostatic field. I want to move this charge from point A to point B and determine the voltage between the two points. Points A and B are the ...
oh no's user avatar
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Why is my idea of voltage drop wrong?

when battery is connected to 2 ends of a wire, potential difference is created, this causes electric field causing electrons to move, the field gives the electron electric potential and the thus ...
Anton Bert's user avatar
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When Can a Set of Surfaces Be Equipotentials?

The question on the title is the name of the section 5.0.0. of Smythe's book on electromagnetism. He explains this question very briefly, but i genuinely do not understand the argument. The page in ...
QuantumBrachistochrone's user avatar
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In layman’s language what is the difference between stopping potential and work function?

In layman’s language what is the difference between stopping potential and work function? It feels like both the things mean the same thing, if I am wrong please explain the things to me.
User_5117's user avatar
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I don't understand Green's derivation of the Laplace/Poisson equation inside an electrically charged body

I am currently reading George Green's "An Essay on the Application of Mathematical Analysis to the Theories of Electricity and Magnetism"Green's essay to gain some insight into the original ...
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From where does this equation of quadrupole potential of a quadrupole mass filter derive from?

Quoting from thesis "Chip-scale quadrupole mass filters for a Micro-Gas Analyzer" (page 23): As I am solving quadrupole mass filter equation, I am stuck from where quadrupole potential ...
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Charge distribution in two concentric conducting shells connected by a thin wire

Above is the content of the problem in the title and I'm confused about the solution. I'm not sure whether it is correct or not. The two shells are conducting and connected, so the difference in ...
Miłosz Brzechczyn's user avatar
2 votes
1 answer
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Alternative potentials in the context of spontaneous symmetry breaking

Consider a one-dimensional real scalar field $\phi$. Usually when spontaneous symmetry breaking (SSB) with such field is discussed, the following potential is assumed: $$V=-\mu^2\phi^2+\lambda \phi^4$$...
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Self-Energy of a Conducting Shell based on Surface Charge Distribution

If a charge $q$ is given to a shell of radius $r$ (conducting or non-conducting) it's self-energy is $kq^2/2r$, $k$ being Coulomb's constant. But if the shell is conducting and the charge on the inner ...
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When is minimum potential energy in simple harmonic motion not zero?

We know that in simple harmonic motion, potential energy is minimum at the mean position and it is zero since displacement is zero. So what are some cases in which minimum potential energy is not zero?...
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Simplified Explanation of Coleman-Weinberg Potential in QFT

I have been reading a research paper where the interaction potential between two scalar fields is given by $$=g\, \phi H^\dagger H .$$ The Coleman-Weinberg correction to the potential is: $$ \frac{n}{...
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Why is the electric potential from a positive sphere not negative? [duplicate]

Say we have a positive point charge located somewhere. Then the electric field due to this point charge is $\vec{E} = \frac{1}{4\pi \epsilon_0}\frac{Q}{r^2}\hat{r} $ , now considering potential is $V =...
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Surface charge density within a parallel plate capacitor on different voltages

I need a way to vary the surface charge density without changing the electric field. My idea is to use two large conducting parallel plates close to each other in vacuum enclosed in a grounded vessel (...
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Thermodynamic work and potential functions

I was reading about the maximum thermodynamic work of a system (Z) that is going to equilibrium. \begin{equation} dZ = dU + p_0 + T_0dS \end{equation} I then came across the thermodynamic potential ...
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Electric field at any point in the region between two capacitors is proportional to the magnitude of charge on each conductor

This is a statement from Young and Freedman's University Physics Section 24.1 on Capacitors. Suppose we have any two conductors with charges $-Q$ and $+Q$ on each charged with a battery. Then this ...
nomadicmathematician's user avatar
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2 answers
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Potential of an electric dipole

I'm currently working my way through Griffith's Introduction to Electrodynamics (4th ed). In chapter 3 section 4, he shows that we can take the equation for the electric potential of a continuous ...
ReggiePlasmaQs's user avatar
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Is there a deeper relationship between symmetry and gravitational potential comparing Newton's and Einstein's gravity?

In this question, see Why is general relativity in (2+1) dimensions different from cylindrical systems in (3+1) dimensional GR?, it is mentioned "The gravitational potential Φ of an infinite rod ...
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How do charges on two conductors charged by the same battery relate to each other?

Let’s consider 2 neutral conducting spheres, L and R, with different radii. There is a battery somewhere in the middle between these spheres. The battery has potential $\phi_{B-}$ on its negative ...
Alexandr's user avatar
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Potential on conducting shell without image charge

Edit 2: I know how image charges work. But I'm still trying to rationalize without it. Edit 1: scrap this, realized what I needed was image charges. This entire question is sort of a jury-rig ...
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How to describe the dynamics of a magnetic monopole charge in the external EM field using a Lagrangian in terms of the EM potentials?

The equation of motion of a magnetic charge in the fixed external electromagnetic field $\mathbf{E},\mathbf{B}$ is $$ \frac{d}{dt}(\gamma m \mathbf{v})=q_m(\mathbf{B}-\mathbf{v}\times\mathbf{E}), $$ ...
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A General Analysis of Charge Distribution inside conductors

I'll go ahead and present my question straight-forward and then talk about the calculation details.My Question is: how do you define a conductor in Electrostatics? What are the basic(minimum) set of ...
Charu _Bamble's user avatar
5 votes
2 answers
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Long-range approximations of the Uehling interaction

A common approximation to the \begin{equation} U(\vec{r})=-m\frac{\alpha(Z\alpha)}{\pi} \int_1^\infty\mathrm{d}u\frac{\sqrt{u^2-1}\left(2u^2+1\right)}{3u^4}\frac{\exp(-2mur)}{mr} \tag{$\star$} \end{...
dennismoore94's user avatar
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6 answers
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What is electromotive force? What's its relationship to Voltage? + clarification of confusion

So first of all, yeah I know that the electromotive force is not a force (the name was coined by Alessandro Volta I think). About Power and dissipated power The power with wich a battery provides the ...
Manuel's user avatar
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$\pi$ phase shift upon reflection in quantum wells

Is there a similar phenomenon to the $\pi$ phase shift experienced by light upon reflection from a medium of lower to higher refracted index for particles in different potentials? For instance, does a ...
TheorVHP's user avatar
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3 answers
49 views

How is electric potential the work done on a unit charge?

I recently read that electric potential at a point is defined as work done in bringing a positive unit charge from infinity (or any other reference point) to that point. How can electric potential be ...
Anvi Mahajan's user avatar
2 votes
0 answers
114 views

What are the limitations of Nodal Analysis?

Yea, that's the question basically. What are the limitations of Nodal Analysis? Like, for example take the following case, we have to find out the net capacitance between A and B. Now I want to solve ...
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Vector potential of Weird loop

I have to calculate the vectorpotential of a current flowing through the loop at the origin: where the current is given by $I(t)=kt$ for some $k>0$. Given equations $$\mathbf{A} = \frac{\mu_0}{4\...
want2know's user avatar
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How does 1D Schrödinger equation arise out of the postulated 3D Schrödinger equation and solving 1D particle using 3D Schrödinger equation?

I've stumbled upon this question when I was trying to solve the Schrödinger equation for a particle confined to a 1D line with some given time independent potential $V(x)$. The energy eigenstates ...
Arjun's user avatar
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Equipotential surface of Hemispherical charge distribution

I was attempting a question of electrostatics from the book Pathfinder for Olympiads and Jee advanced Physics. In a solution of certain question, the base of a uniform hemispherical charge ...
Navanieeth TS's user avatar
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Hydrogen atom energy: $n$ vs $l$ (QM)

I've come across a problem that states the following: let two (separate) particles be subject to a central potential $V(r)$. Their reduced radial function is depicted in the following image: Which ...
Lagrangiano's user avatar
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Method of images and the zero potential of the conductor

I was reading the method of images in Griffiths' electrodynamics book. He uses the classic image problem to explain the significance of the uniqueness theorem suppose a point charge $q$ is held a ...
Hello's user avatar
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4 votes
1 answer
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Series Solution of Laplace Equation in Spherical Coordinates

I was recently Studying Griffiths Electrodynamics after a long time and there I saw the Laplace equation. Because it was my second time going over Griffiths so I thought maybe I should try to derive ...
Charu _Bamble's user avatar
2 votes
0 answers
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Time evolution of scalar potential using Huygens principle

Huygens principle states that every point in space acts as a source of spherical waves. The amplitude for potential (scalar and vector) will be given by $V(r,t)=f(t-r/c)/r,$ where $f$ is a function ...
Physics's user avatar
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The electrostatic potential due to a pair of oppositely charged infinite thin conducting plates

The electric field in region A and C (outside the pair of sheets) is 0. The electric field in region B (between the plates) is given by: $$E = \frac{\sigma}{\varepsilon}.$$ The distance between the ...
Aaditya Jain's user avatar
1 vote
0 answers
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Electric field due to plane at constant potential and a cylinder with no flux on surface

There is a plate at a constant potential V and potential equal to zero far away. the problem is two-dimensional. For this case, the electric field lines will simply be straight lines. Now let there be ...
nameDisplay's user avatar
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2 answers
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Potential attained by a sphere under illumination

A silver sphere of radius 1 cm and work function 4.7 eV is suspended from an insulating thread in free-space. It is under continuous illumination of 200 nm wavelength light. As photoelectrons are ...
Nandini's user avatar
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2 answers
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Potential on concentric shells not making sense?

Suppose you have 2 concentric spherical shells, radius $A$ (inner) and $B$ (outer). Now suppose the inner shell has $+Q$ charge and the outer one has $-Q$ charge. Through integration, we get that the ...
AankNum's user avatar
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10 votes
2 answers
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Is work done by a charged particle not gauge invariant?

Work done by a charged point particle with charge $q$ in an external electric field derived from a scalar potential $\phi$ is given by $$W=q \phi.$$ Even if we add a magnetic field the definition ...
user avatar
1 vote
1 answer
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What is the potential of a conductor between two eletrically-charged plates?

Let's say I have two plates. One is at +20V, the other is at +10V, and they are separated a meter apart. I place an uncharged conductor that's 10cm wide into the gap between them, 20cm from the plate ...
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It's possible to have different potentials (boundary conditions) in the surface of a cylindrical conductor?

Edit I realized that my problem is not clearly stated. In general, I can solve the Laplace equation for boundary conditions $V(r,\phi, z=0) = f(r,\phi)$ (bottom of the cylinder), $V(r,\phi, z=L) = g(r,...
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3 votes
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Question about Fourier-coefficients in Griffith's Problem 3.15 (Electrodynamics) [closed]

I am having some trouble with problem 3.15 from Griffith's Electrodynamics. It states the following: A rectangular pipe, running parallel to the $z$-axis (from $-\infty$ to $+\infty$), has three ...
want2know's user avatar
1 vote
1 answer
42 views

Why does the stopping potential correspond to zero current?

My textbook has derived an equation for the stopping potential during the photoelectric experiment as follows: $$\frac{1}{2}mv_\text{max}^2=eV_0 \\ \implies V_0=\frac{mv^2_\text{max}}{2e}\implies V_0=\...
Schrödinger's Cat's user avatar
1 vote
1 answer
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Electric potential energy, Electric potential and self-energy of a body

The total work done to bring all the charges constituting a body from infinity to the body one by one is called the electrostatic potential energy of the body. And if I divide the expression of ...
Peter swift's user avatar
0 votes
2 answers
51 views

Gravitational potential due to arbitrary shape

Outside the uniform sphere, the potential is expressed as if all the masses are concentrated in the center of the sphere. Is it also true for arbitrary shape? That is, outside any body, is potential ...
SungJin Park's user avatar
3 votes
5 answers
1k views

Can a positive charge have a negative potential?

I'm studying about electrostatic potential due to a point charge and was wondering - can a positively charged point have negative electrostatic potential? V=Kq/r for a positive point charge. Assume B ...
Mel's user avatar
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What does 0 volts mean for a Van de Graaf generator?

I am trying to understand how two different definitions of zero-voltage reconcile in the experimental setup of a Van de Graaf generator, or at least how I understand that it is being described. ...
lamplamp's user avatar
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Uniqueness Theorem and boundaries conditions

I was recently studying Jackson Electrodynamics and faced some issues directly. I have studied Griffiths Electrodynamics and I knew about the uniqueness Theorem from it. But in Jackson, they proved it ...
Charu _Bamble's user avatar
1 vote
1 answer
33 views

Does it make a difference whether potential difference is denoted as a negative or positive value in an answer, since it's just a scalar? [duplicate]

Does it make a difference whether potential difference is denoted as a negative or positive value in an answer, since it's just a scalar? Sorry if it's a dumb question, I was just a little unsure.
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