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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2 answers
561 views

Numerical calculation of electric field in dielectric medium

I want to numerically calculate the electric field between two parallel plates with finite length. Where parallel plates are connected to source of constant potential difference: I have boundary ...
-1 votes
0 answers
20 views

Calculation of Average Position for Particle in Infinite Potential Well [closed]

I am working on a problem involving the calculation of the average position for a particle confined to an infinite potential well. The ground state wave function � ( � ) ψ(x) is given by: � ( � ) 2 � ...
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We have calculated the gravitational potential due to a disc or ring at its axis || My challenge to all physics lovers, calculate it at height h above [closed]

It is a given disc with a defined mass, radius and mass per unit length. Assuming disc's centre to be origin (0,0). Find the gravitational potential due to disc at point a(x, h). Please don't classify ...
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1 answer
36 views

Equation of a equipotential surface

I have been trying to find a equation for the equipotential surface of a dipole , so I started with a simpler system of a singular charged particle , here are few things I know about the equipotential ...
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4 answers
117 views

Why does the capacitance of a capacitor depend on charge and potential?

The formula of capacitance is $$C = \frac{Q}{V}.$$ So the capacitance of a capacitor should depend on the charge and potential but it doesn't. Why?
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0 answers
15 views

How to transform the volume integral of a curl of the product of a potential with a magnetic field into a surface integral?

Problem 6.5 of Jackson electrodynamics says: A localized electric charge distribution produces an electrostatic field, $\vec{E} = - \vec{\nabla}\Phi$. Into this field is placed a small localized time-...
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1 answer
318 views

Sign of shaft work done when piston moves upward

If the piston shown above moves upwards a distance 1 m the shaft work (according to the textbook solution to a related problem) is 1334 J. Shouldn't the sign of work be negative because the shaft ...
17 votes
1 answer
8k views

3D Delta Potential Well

The 1D delta potential well $V(x) = -A\delta(x - a)$ always has exactly one bound state. The same is true for the 3D delta potential well $V(\vec{r}) = -A\delta(\vec{r}-\vec{a})$. I can show this for $...
26 votes
3 answers
15k views

Why the statement "there exist at least one bound state for negative/attractive potential" doesn't hold for 3D case?

Previously I thought this is a universal theorem, for one can prove it in the one dimensional case using variational principal. However, today I'm doing a homework considering a potential like this:$...
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1 answer
292 views

Potential due to initially uncharged induced conductor?

From Griffiths' Introduction to electrodynamics: In this problem, Griffiths says that we will set the potential inside and on the surface of the conductor to be zero since its an equipotential ...
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1 answer
21 views

Will the potential on surface of a irregular conducting sphere surface be constant?

We know that potential on surface due to a regular conducting sphere is constant. But what will it be when the surface is irregular and charge distribution is non-uniform?
3 votes
0 answers
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What are exactly the loop correction to the potential? [duplicate]

I am struggling with the concept of quantum effective action, but first recall the definition : given a Wilsonian effective action $W[J]$ of our theory, the quantum effective action is just $$\Gamma[\...
3 votes
1 answer
8k views

The vector and scalar electromagnetic potentials of a plane wave

Consider a simple 3D wave solution of Maxwell's equations: $$\vec B=\vec e_z \cos\left(\frac{2\pi}{\lambda}(ct-x)\right),$$ $$\vec E=\vec e_y\cos\left(\frac{2\pi}{\lambda}(ct-x)\right),$$ and ...
-1 votes
5 answers
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Question about Voltage in circuits

What does for example "9V on a battery measure" really measure, is it the electrical potential of a single Coloumb of charge provided by the battery? Is it the potential difference? If it's ...
2 votes
1 answer
43 views

I'm trying to figure out how to go from the electric potential of a uniformly charged semi-circle, to the electric field

The question asks "A thin plastic semi ring of radius $R$ has a uniform linear positive charge density $\lambda$. a) Determine the electric potential $V$ at point O, the center of the semi ring. ...
1 vote
0 answers
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Converting a gravitation potential from spherical to Cartesian and adding arbitrary tilt

I am working on utilising different potentials in my N-body code to do toy simulations (massless particles in a potential. However, I ran into issues converting a certain potential from a paper into ...
1 vote
1 answer
299 views

Clarification on electric potential energy

From what I understand from my notes (correct me if I'm wrong), electric potential energy is the work done in bringing the charge from infinity to a certain point from the source charge. Let this ...
1 vote
1 answer
32 views

Can the potential of a point charge be considered one-dimensional?

It is well known that,take infinity as 0 potential,the potential at position r of a point charge q placed at the origin is $$V = \frac{1}{4\pi \epsilon _0}\frac{q}{r}$$ it satisfies three dimensional ...
1 vote
0 answers
57 views

Vector potential in Poincaré gauge

Dear members of Physics StackExchange, I have recently been pondering the Aharonov-Bohm-effect as it relates to an infinitely long solenoid. Let $R$ be the radius of the solenoid centered on the $z$-...
3 votes
2 answers
378 views

Difference between grounding the inner and outer side of a thick spherical shell

I have a conducting sphere with radius $R_1$ and charge $Q_1$ inside a conducting thick spherical shell with inner radius $R_2>R_1$ and outer radius $R_3>R_2$. Both the spheres have the same ...
0 votes
1 answer
62 views

Is there any finite charge distribution the potential of which doesn't decay with $\frac{1}{r}$ at infinity?

Is there any finite charge distribution the potential of which doesn't decay with $\frac{1}{r}$ at infinity? Intuitively, if you "zoom out" any finite charge distribution, it could be ...
0 votes
1 answer
224 views

Deriving Konopinski's Operational Definitions of Scalar and Vector Potential

In "What the electromagnetic vector potential describes", E. J. Konopinski asserts: Operational definitions of $\phi$, $\mathbf{A}$ should now be expected to stem from the equation of ...
1 vote
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55 views

Probabilistic reformulation of classical Simple Harmonic Oscillator

As an interesting exercise, I was wondering whether we could reformulate classical mechanics in such a way that we could use the same mathematical paradigm we use in quantum mechanics. I'll expose it ...
2 votes
2 answers
637 views

Why does potential of a conductor decreases if a negatively charged conductor is brought near a positively charged conductor?

Also, how should I imagine potential in my mind? How should I picture it?
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2 answers
188 views

What happens step-by-step (and why) when a particle tries to escape an infinite potential well?

I am aware that the following question might be quite elementary. My background is mainly in mathematics and my physics education is limited to high-school level material (discounting analogues made ...
1 vote
1 answer
152 views

Why is probability outside the infinite square well zero? [duplicate]

In an infinite square well, potential energy is given below, why is the probability of finding a particle in the position of infinite potential energy zero? $$V(x)=\begin{cases} 0,& \text{if } ...
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2 answers
71 views

Why doesn't charge accumulate in a loop?

When learning about electromagnetism at my university, electricity flow is generally shown as a conductor with a high potential at one end and a low potential at the other and thus charges flowing ...
0 votes
1 answer
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Circuit without grounding

I'm learning about the notation of grounding. In this post of Wikipedia, https://en.wikipedia.org/wiki/Floating_ground, it is said that Conductors are also described as having a floating voltage if ...
0 votes
1 answer
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One-loop effective potentials and Schwinger's parametrisation

I was reading this paper where they calculate the effective potential of a scalar field $\phi$, which is (without any justification) $$ V_{eff} (\phi) = \dfrac{1}{2} \sum_I (-1)^{F_i} \int \dfrac{d^4 ...
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1 answer
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Dipole potential and sphere grounded

Find the electrostatic potential arising from an electric dipole of magnitude $d$ situated a distance $L$ from the center of a grounded conducting sphere of radius $a$. Assume the dipole axis cross ...
0 votes
1 answer
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How to Derive Potential Momentum?

The only derivation/definition of potential momentum I've seen is using the fact that: $$E^2-p^2c^2=m^2c^4$$ And if you add a potential, you must subtract something else from the momentum called the ...
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2 answers
452 views

Electrostatics - Potential near conductor using Kelvins method of image charge

As the figure shows, I have a 2D image of a conductor seen from the front. It is located a height, h1, above a grounded plane of infinite area. The conductor has a voltage, Vc, as shown. Around the ...
-1 votes
3 answers
212 views

Why something connected to the ground has 0 potential?

I'm studying the concept of grounding of neutral wire in AC. I have done an extensive research on the internet to answer the question "Why the neutral wire has 0 potential ?". The answer is ...
1 vote
0 answers
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Normalizable solutions to the time-independent Schrödinger equation are real [duplicate]

In Griffiths Introduction to Quantum Mechanics (3ed.) problem 2.1, we are asked to prove that the normalizable solutions to the time-independent Schrödinger equation can always be chosen to be real, ...
4 votes
0 answers
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Yukawa potential as the time integral of 4D retarded Green's function

I am attending an advanced QFT course, and trying to verify the instructor's claim that the retarded Green's function $$ G_{\text{ret}}^{(4D)}(t,\mathbf{x}) = \theta(t) \left[ \frac{1}{2\pi}\delta(\...
4 votes
2 answers
176 views

Parity of a bound state determined by potential

Some time ago in my QM class, we were working with an infinite well potential, and my professor told us we could know beforehand the bound states we were going to obtain for said potential would have ...
1 vote
2 answers
43 views

Sign Problem When Calculating the Potential of an Infinite Line Charge [duplicate]

Similar questions have been asked before in the forum regarding the sign problems when integrating the electric field, but they do not fully clarify the problem for me, so I just want to ask for some ...
-1 votes
3 answers
514 views

Why do we use negative sign for electric potential/voltage?

Negative sign is used for electric potential belonging to negative charge but whenever in electrostatics the "negative" sign is referencing for example: force means its attractive or ...
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1 answer
33 views

Electric potential inside a conductor due to a point charge outside the conductor

I am a highschool student. I recently learned about conductors with cavity in school. How does a point charge outside the cavity, kept at a certain distance from the conductor, affect the potential of ...
1 vote
1 answer
655 views

The link between two definitions of "potential density"

In Kundu's book , 4ed, P21, they define the potential density $\rho_\theta$ like this: However, later in P22, they define the potential density gradient as It seems to me that the potential density ...
1 vote
2 answers
268 views

Charged plasma and ion grid in interaction in ion thrusters

I was just wondering ..... In this Image of an ion thruster, when the positively charged particles pass through the grids, wouldn't they just bombard the negatively charged grid(a fraction of them). ...
0 votes
1 answer
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How do I find the wavefunction equation for a translated potential? [closed]

Let me explain myself. In my case, I know the wavefunction equation of a infinite-U potential which has the form: $$V(x)=\begin{cases} V_0,\ \ |x|\leq \frac a2\\ \infty, \ \ |x|>\frac a2\end{cases}$...
0 votes
2 answers
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Solving the Inhomogeneous Wave Equation

This question is based on a problem from JD Jackson's Classical Electrodynamics, which asks for the solution of the inhomogeneous wave equation: $$\frac{1}{c^2} \frac{\partial^2{A^{\nu}}}{\partial t^...
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1 answer
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Potential difference between electrolyte and electrodes in terms of electrostatics concept

As a high school student studying electrostatics, I understand that the electric potential at a point closer to a charged particle, is nearly infinite, then why there exist a finite potential ...
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0 answers
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CMB anisotropies due to moving clusters/voids?

Apparently, there is an effect where a moving overdensity/underdensity (or an object, e.g. a galaxy, moving in an overdensity/underdensity) that is going through an evolution of its gravitational ...
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0 answers
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How do we define electromotive force and potential difference in terms of energy transfer between energy stores?

I understand that energy is transferred electrically from the chemical potential store in the battery to internal store of the resistor. How do we include the energy transfer in the definitions of ...
1 vote
2 answers
96 views

Defintion of gravitational potential

I am not much clear regarding the defintion of "gravitational potential": Is the work done for bringing the unit mass from infinity to that point by, gravitaional force or external force? (...
1 vote
1 answer
32 views

Electric Field and Potential between two infinite sheets with multiple dielectric mediums [closed]

Suppose we have 2 infinite sheets, one lies on $z = 0$ with potential $V = V_0$ and another at $z = a + b$ with potential $V = 0$. There are two slabs of dielectric material with permittivity $\...
2 votes
2 answers
262 views

Vector potential of position field

Consider the position vector field $\vec{r}=(x,y,z)^T$. What would be a vector potential $\vec{A}$ for this field? I was thinking of something like $\vec{A}=(yz,zx,-xy)^T$, which gives $$\nabla\times ...
0 votes
1 answer
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Potential inside metal sphere in field of external charge [closed]

If a have a arrangement like-( Where r is radius of hollow conducting sphere with centre C and Q is point charge) Then what is potential at any point between P and C? I think first we need to find ...

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