Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

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.

1
vote
1answer
41 views

Question about fundamental states on an finite well

My question is the following, when we search for the bound states a finite well potential we have solutions symmetric and antisymmetric so we get two families of solutions. In this case, the ...
1
vote
3answers
181 views

How do we deduce the vector potential for a constant magnetic field?

How do we show that for a constant magnetic field $\vec B = const$, the vector potential is $\vec A = \frac12 \vec r \times \vec B$?
0
votes
1answer
23 views

Interactions between “particles” to prevent diffusion and to cause phase segregation

The free energy of particles reads, if we assume no internal energy : $\tilde f(c)= \frac{f(c)}{k_bT}=-c \, ln(c)-(1-c)\, ln(1-c)$, with $c$ the concentration. If we had a term $F(c)$ for the ...
1
vote
4answers
74 views

What is the difference between the voltage in the electrical circuit and electrostatics?

In electrostatics it depends on the distance from the charges, should it also be in the circuit? But in practice, the voltage depends on the resistance, for example on a resistor. And the distance ...
6
votes
4answers
310 views

Electron travelling through a step potential from $V_0$ to 0

Most of the time you discuss the step potential case when $E>V_0$, you consider an electron (or a beam of electrons) travelling from a region of space $x<0$ in which $V=0$, to a region $x>0$ ...
1
vote
1answer
77 views

How can Young modulus depend on the geometry of the item & Lennard Jones (question related to an older one)

In the question Young's modulus and geometry of test material, the answer was that it cannot play any role. Nonetheless, for the Lennard-Jones solid, in many places the Young modulus is given as : ...
0
votes
1answer
76 views

Confusion in work done in moving charge to infinity from center of conductor

A point charge $q$ is at center of spherical conducting shell of inner radius $a$ and outer radius $b$. Find work done in moving charge to infinity. The answer (given in book) is: $$W = \frac{q^2}{8\...
4
votes
2answers
202 views

What are the energy eigenvalues of a particle subject to the potential $V(x)=mg|x|$?

I am considering a particle within a potential given by $$V(x)=mg|x|$$ and am attempting to find the energy eigenvalues of the system. Taking $V(x)$ to be defined piecewise, I've solved the ...
1
vote
1answer
74 views

Equilibria and conserved quantities in a superposition of central potentials

I have a Lagrangian made up of a superposition of $k$ central repulsive potentials centered at $(a_k,b_k)$. Each potential is somewhat strange - they take the form $V(r)=-\ln\left(r\right)$. The whole ...
1
vote
1answer
98 views

Coaxial cable with infinite return conductor

If a coaxial cable has a coaxial return conductor with infinite outer radius, will the return conductor experience a voltage build-up due to current flowing through it, or will it stay on ground ...
0
votes
1answer
27 views

Does an external perturbing potential appear in the gravitational Poisson equation

We could use any self-gravitating fluid for this question, but let's take a star as an example. Left alone, it's density is the source of it's potential and thus we have the simplest form of Poisson's ...
2
votes
1answer
47 views

Difference, in terms of completeness, between the Dirac well and barrier

I was in my undergraduate QM lecture and we just finished with the Dirac barrier. My question is as follows: We know that the Dirac well’s complete set of solutions requires one bound state and an ...
0
votes
2answers
128 views

Potential difference in a nonuniform electric field

Let's say I have two points in a nonuniform electric field and those points have the electric potential 10 V and 5 V. If I then would use a voltmeter to determine the voltage between those points ...
1
vote
4answers
149 views

Why do we assume that Earth and infinity are at same potential?

In many standard texts I have seen the approach of taking any point connected with Earth in a circuit as 0 potential. Obviously, there is nothing special with 0 as long as we are concerned with ...
-2
votes
1answer
60 views

Given the parameters of the electrostatics problem, is this integral possible to evaluate analytically? [closed]

A cone with apex at the origin has a height $h$ and a top radius $h$, a uniform charge density with no charge on the top face. I need to find the potential $V$ at a position $z$ on the cone's axis ...
-2
votes
2answers
50 views

How to calculate the potential and electric field everywhere if we know the electrostatic potential on the surface of a cylindrical? [closed]

I know that electric field $E=-∇V.$ But since the only given parameter is the potential on the surface. Is it possible to calculate the potential everywhere (positions besides the surface)?
3
votes
1answer
78 views

Power series solution for a shifted spherical harmonic oscillator

I'm trying to solve the Schrodinger equation for a radial Harmonic oscillator whos equilibrium point has been shifted away from the origin, i.e. $V(r) = V_0(r-1)^2$. The standard approach is to make ...
1
vote
1answer
28 views

How does the image of $\sqrt{2/L} \ \sin\left({k_n x}\right)$ satisfy the boundary conditions for the infinite square well?

I understand mathematically how $\sqrt{2/L} \ \sin\left({k_n x}\right)$ satisfies the boundary conditions for the infinite square well in terms of the fact that $\psi(0) = \psi(a) = 0$, and excuse the ...
1
vote
3answers
87 views

Potential Gradient relation [duplicate]

I was just wondering why exactly the force is the negative gradient of the potential, which is shown by the relation $${\bf F}=−{\bf∇}V$$I know that this equation only holds for conservative forces, ...
0
votes
1answer
22 views

Voltage in an inhomogenous electric field

In a homogenous electric field, we know that the voltage is U=Es. But in an inhomogeneous electric field is there any way to calculate the voltage at some point or between two points?
-1
votes
3answers
128 views

What determines the voltage in a battery?

This diagram problem has got me thinking about what determines the voltage in a battery. At school, we were taught this method of giving a value of voltage to points in a circuit. However, I do not ...
0
votes
2answers
36 views

Why should the spherically asymmetric part of the effective potential be small in the central field approximation?

In the central field approximation, each electron is supposed to move in an effective or average potential contributed by its attractive interaction with the nucleus and repulsive interaction with the ...
0
votes
2answers
74 views

Work done by electric field in a wire

Work done by electric field in moving a unit charge is the potential drop. In wires voltage (potential drop) is given by ohms law. Can somebody explain to me why work done by electric field can not be ...
5
votes
2answers
302 views

Physical Significance of $U$ (Internal Energy ) , $H$ (Enthalpy) , $F$ (Free Energy) and $G$ (Gibbs Free Energy)? [closed]

I know their mathematical definitions and how these terms are interrelated (mathematically) but I fail to understand the physical meaning of none but one which is INTERNAL ENERGY . It seems ...
0
votes
1answer
146 views

What is the difference between EMF of a battery, its potential difference and the current supplied by the battery?

Now, I know that emf is measured using an ammeter, while potential difference is measured using a voltmeter. But why is that so? What do we mean when we say the emf of the battery is say, 3V, and the ...
0
votes
5answers
198 views

What exactly is “voltage drop” across a circuit element?

what exactly is "voltage drop" across a circuit element? I don't quite understand what this means.
1
vote
1answer
212 views

Fourier tranform of Coulomb-like potential $1/|r-r'|$

I've found that Fourier transform of Coulomb potential $V= q/r$ is $F[V]= 4\pi q/k^2$. Now I need to calculate fourier transform of function $1/|r-r'|$. And I exactly don't know how to operate with ...
2
votes
1answer
78 views

Electric potential - Batygin, Toptygin book

I found in Batygin and Toptygin problems in electrodynamics a particular problem: Density of charge is $$\rho = \rho_{0}\cos{\alpha x} \cos{\beta y} \cos{\gamma z}$$ in whole space. Find electric ...
0
votes
1answer
42 views

Introducing stream function with given velocity equation

Bit information about the problem We are dealing with the slide coating process - where basically a polymer is being put onto a slot, which is moving in the $x$-direction with velocity $v_0$. The ...
0
votes
2answers
69 views

Potenial difference from electric field and line integral

I am really confused about the relation of potential difference and the electric field. The relation between potential and electric field is $$V_{ab} \equiv V_a - V_b = -\int_{b}^a{\vec{E}\cdot\vec{...
0
votes
3answers
471 views

Electric field in spherical coordinates

Let's say I want to find the line integral of the electric field along some path $ab$ as shown here I imagine taking small segments $dl$ of that path from $a$ to $b$, but as I imagine that, I ...
1
vote
3answers
77 views

Why does the full PD across a battery manifest itself across a break in a circuit at any point?

Consider the following circuit: I want to know why the full pd of the battery can be measured across the break if a voltmeter was connected. Surely when the whole circuit was closed the charges at ...
0
votes
1answer
84 views

field lines in a grounded conductor next to a charge

let us imagine we have a charge and a conducting grounded sphere at some distance. The sphere will be charged but at zero potential. However, if I try to compute the potential using the integral of ...
1
vote
1answer
65 views

Electric Potential drop in wires

Electric potential is related to Electric Field by negative integral of Field with distance.If charges move away from the positive terminal (Assuming conventional flow) why is there no drop in ...
1
vote
2answers
52 views

Can two different points have the same potential?

I have read in my textbook that the flow of current takes place till there is a potential difference between the two points and stops when they acquire the same potential, but how can two different ...
0
votes
1answer
192 views

Electric Potential of Non-Uniformly Charged Infinite Plane

A little background: I was tutoring an undergrad upperclassman when we came to a problem that he had been assigned which I couldn't make heads or tails of - at least in terms of what was being ...
2
votes
0answers
65 views

What does it mean for a potential not to have a Fourier transform?

Consider an isotropic potential $\phi(r)$ corresponding to the classical force of interaction between two point-particles. The Fourier transform of this potential $$ \Phi(k) = \int \exp(-i\vec k\cdot\...
0
votes
0answers
16 views

Finite potential well without using even/odd symmetry

This is a follow up question to this question. I tried using the hint in the accepted answer to get the tangent equations but when I divide the equations at $x=-a$, I get: $$\begin{align} \kappa &...
1
vote
0answers
35 views

What type of potential is suitable for ion bombardment in Molecular Dynamics?

I would like to study ion bombardment on targets with molecular dynamics, especially on oxides. So far I ran conclusive tests with Lennard-Jones potentials, but I would like to obtain better ...
0
votes
1answer
30 views

What's Gravitational Potential Energy of a Balanced Mass on a single Point?

Anyone know how to calculate the gravitational potential energy of a balanced Mass such as an upside down 2d triangle balanced on a single point. Is there any way to calculate the gravitational ...
0
votes
1answer
47 views

Electrostatics: Potentials and Minus signs

I've got a simple question regarding electric potentials in electrostatics. My book defines electric potential V as $$ V(b) = -\int_a^b \mathbf{E}\cdot d\mathbf{l} $$ where A is defined as where ...
1
vote
0answers
39 views

How to arrange charges on a 1d line so that the electric field along the line far away is r^-6? [closed]

My question is simple: How to arrange charges on a 1d line so that the electric field along the line far away is r^-6?e.g., we can make field falling as r^-3 by two charges(dipole field). This type ...
-1
votes
3answers
464 views

Current in series circuits [duplicate]

Current is calculated according to the resistances in a circuit. Then, why is the current same everywhere in a series circuit? Shouldn't a greater current pass through the smaller resistance? I am ...
1
vote
2answers
61 views

Why does inflation end when the potential becomes too steep?

Inflation ends when the potential becomes too steep. Is it because kinetic energy increase when the potential becomes steeper?
1
vote
0answers
64 views

Two dimensional hyperbolic potential has no charge density but a surface charge density?

I am learning about electric potential, and I am confused about what exactly is going on in the following situation: Say we have a potential $V =- V_0 \frac{xy}{a^2}$ This means that $\nabla^2V=0$. ...
0
votes
2answers
63 views

How can I show the negative gradient of centrifugal potential equals centrifugal force?

Given, the centrifugal potential is $$V = -m\frac{1}{2} \left\lVert\ \vec w\ \times \vec r\ \right\rVert^2 $$ I simplified, $$V = -m\frac{1}{2} (w^2 + r^2) $$ ,converted to Cartesian $$V = -m\...
1
vote
2answers
59 views

Definition of Voltage using integral: minus sign?

So I'm studying electrostatics and I came across to two different definitions of potential difference/voltage (because we're in stationary regimes) and I'm having trouble understanding how the ...
1
vote
1answer
419 views

Electric field from a quadrupole

In the following problem, I have already solved for the value of the potential, and I would like to tackle the extra exercise, which asks for the electric field of a point quadrupole: At every ...
2
votes
1answer
510 views

Average electric field calculated from average potential

In a Griffiths problem (3.4) I'm asked to find the average electric field over the surface of a sphere due to point charges inside/outside the surface. The calculation is done in his solutions ...
0
votes
1answer
97 views

Electric potential everywhere around an infinite slab

The problem: Consider an infinite slab with uniform charge density $\rho$ between two planes $z=\frac{d}{2}$ and $z=-\frac{d}{2}$. Find the electric potential $V$ in the entire space and plot $V$ ...