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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Is electric potential at a point defined due to an “isolated” point charge?

If there is a fixed point charge then it has its fields in the surrounding and it doesn't matter whether there is another charge near or not. But for potential, it is defined as electric potential ...
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Confusion with Electrostatic Potential Difference

Suppose that you have a positively charged plate at a plane (xy-plane, for example). Therefore this plate exerts an electric field with a magnitude of σ/2ε₀. Due to this, there will be the same ...
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Solid Conducting sphere is placed inside a metallic shell the conducting sphere is given a charge Both are connected does all charge flow to the shell [closed]

Here the solution says that all the charge goes into the outer shell, is this correct ? If then why ? Shouldn't the charge transfer happen until the potentials of the outer shell and inner conductor ...
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Solving poisson equation of point charge using integration

I want to solve the poisson equation of a point charge at $\vec{r}=0$ using integration. But I got some problems So the equation that needs to be solved is: $$ \bigtriangleup\phi=-4\pi\rho \Rightarrow\...
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Measuring Potential of a Conductive Sphere [closed]

Question: Mim is trying to measure the potential of a conductive sphere. So he connected that sphere with another sphere of 220V potential with a lead of pencil that has a length of 50cm and ...
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Finding the energy stored in an spherical shell, but integral diverges

I am attempting to find the energy stored in assembling an spherical shell (denoted by $S$) uniformed distributed of total charge $q$, and radius $R$. To do so, I want to use the formula: $$W = \frac{...
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Potential difference across two points in a current-carrying wire [duplicate]

I have had this doubt for quite a while and I have tried reading answers to similar questions but I'm still not sure. If I connect a voltmeter at A and B, what would be the reading? Is it going to be ...
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How does current flow in a Van de Graaff generator?

If a Van de Graaff generator mechanically moves charge from low potential to high potential, then how does the charge actually flow onto the sphere? I'm hearing that a spiky conductor ionizes the air, ...
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How to know unstable and stable orbit from a given potential? [closed]

A particle of mass $m$ having a non-zero angular momentum of magnitude $l$ is subjected to a central force potential $$V(\vec r)= k\ ln(r) $$ where $k$ is a constant and $r =|\vec r|$, what is the ...
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Why there is a potential difference only across resistors?

I don't understand why there is a potential difference only across resistors, shouldn't the electrons convert potential energy all the way to the other side of the circuit just like a ball would do ...
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Two infinite grounded conducting planes at a distance $d$ apart. A point charge $q$ is placed in the region between them. What is the potential? [closed]

What does $\Phi$ means in the solution? Is the coordinate of cylindrical system, then $\Phi=\sqrt{x^2+y^2}$?
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Why is the potential inside a hollow metal spherical shell with a point charge $q$ at the center equal to $kq/r+kq/b-kq/a$ rather than $kq/r$?

I'm reading Section 20-6 of Tipler's Physics for Scientists and Engineers, where the potential in and around a hollow conducting spherical shell (inner radius $a$, outer radius $b$) with a point ...
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Conflicting answer for potential of dipole at midpoint

If I have a dipole of two opposite charges separated by a distance $d$, then by taking the leading non-zero term in multipole expansion centered about their midpoint, I find the potential to be: $$ V= ...
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Charge on parallel conducting plates

In this figure, where will the charge go if we have earthed both the plates? I am having some trouble figuring this. Will the charge $q$ on the first plate flow towards the Earth (Case 1), or will it ...
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How is the work done along an equipotential line zero?

If a charge is brought from some distance to a point which lies on the equatorial line of an electric dipole, the work done is 0 and so is the electric potential. But how should I imagine this?
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Why is potential on a conducting shell always constant?

I've read that electric field inside a conductor is zero, and that potential of a two points say A and B on the surface of the conductor is same (constant). The latter puts me in a state of confusion. ...
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Electric potential and fields

In electrostatics, what's the importance of potential, why can't I just just talk about electric field and force one charge has? Also besides that it's the negative gradient of electric field, is ...
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Why is the electric potential for a point charge is $V=kQ/r$ but for the capacitance of parallel plate , the electric potential is $V=E*D$? [duplicate]

From what I've learned since now, I always knew electric potential is inversely proportional to radius or distance for a point charge, but I've come across the electric potential in a parallel plate ...
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The difference between $V=kQ/r$ and $V=ED$ ($V$ is electric potential)? [duplicate]

I realize $V=kQ/r$ is the electric potential of a point charge while the other one is the electric potential in a uniform electric field, but in the first case the distance (radius) is inversely ...
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Ferrocell and Quantum Decoherence

Looking upon the image shown through this device, known as the ferrocell, puts one in a position to engage in some phenomenological operation in order to know what, how and exactly why it appears in ...
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Finite threshold value for two-body binding

In his book Introduction to Superconductivity, Second Ed., Chapter 3.1, when discussing Cooper's 1956 paper and the formation of Cooper pairs, Tinkham states [...] it is well known that binding does ...
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Are the differentials of the three thermodynamic functions $ U $, $ H $ and $ F $ only valid for ideal gases?

I hope you are excellent, excuse me I would like to ask you about the validity of the following differentials of the thermodynamic functions $ U $, $ H $ and $ F $: Are they only valid for ideal ...
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Lack of a name for the Thermodynamic potential wrt the natural variables

From the first law of thermodynamics relation and using Legendre Transform of the Internal Energy, we can possibly define 8 Thermodynamic potentials out of which we know 5. I could not find any names ...
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Internal and external gravitational potentials $V(r)$ of a spherical object of matter of constant total mass $M$, and variable radius $R$

$\newcommand{\oiint}{\iint\limits_{\partial V}\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\!\;\;\;\subset\!\supset }$ Imagine a ball of dust of total mass $M$ and radius $R$. The total mass of the ball remains ...
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Potential of a conductor with cavity and charge

Consider a conductor containing a charge $q$ inside its cavity. Clearly, a negative charge $-q$ will be induced on the surface of the cavity. Let S denote the system of $q$ and $-q$. In a discussion, ...
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How the Hamiltonian's spectrum changes adding a new potential?

I'm trying to answer this question: A free particle with mass $m$ is subject to the potential $$V_0=\begin{cases}0&x\in[0,a]\\+\infty&\text{otherwise}\end{cases}$$ So we have an infinite ...
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How does a particle passing an atom perturb the atom's QM system?

Consider the quantum mechanical system of an atom with Hamiltonian $\hat{H}_0$ and assume that we know the solutions of the eigenvalue problem $\hat{H}_0|n\rangle=E_n|n\rangle$ for $n=0,1,2,\ldots$. ...
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Electric field discontinuity

When there is a charged spherical shell for example, I can calculate its charge using: $$(\vec{E_{out}}-\vec{E_{in}})\cdot \hat{r} = \frac{\sigma}{\epsilon_0}$$ We generally ignore external electric ...
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Superposition of potentials

I'm trying to understand what superposition of potentials means. For example, let be $$V_0(x) = \begin{cases} 0 &x \in [0,2a]\\ +\infty & \text{otherwise}\end{cases}$$ and $$V_1(x)=-\lambda\...
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What is the minimal time to move from the left to the right in a double potential well?

Consider a particle in a double potential well with Hamiltonian $\hat{H}$ and two basis states $|l\rangle, |r\rangle$ which correspond to the particle being maximally localized in the left resp. right ...
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How does the Fermi level of different materials reach equilibrium when in contact?

I'm a college student studying semiconductors. I can't understand what is happening inside the materials when two or more different materials are in contact. Can I get some help? So, basically at ...
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Why is the mass term a part of the potential in Quantum Field theory?

I am currently reading the chapter on scalar fields from the book 'Quarks, gluons and lattices' by Creutz and he mentions that "The full potential felt by the [scalar] field $\phi$ includes the ...
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Why is it selectively OK to rely on intuitive analogues when solving problems in Quantum Mechanics, such as the step potential problem?

I was looking at solved example (3.13) in the Schaum's Series book on QM by Yoav Peleg et al (2nd edn), where they solve for a step potential where a high energy particle is coming from the left and ...
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How did Feynman derive the potential energy of the ballistic galvanometer?

In the Feynman Lectures Vol 1. Chapter 41 - The Brownian movement, the following statement is present under Section 1 - We know the formula for the kinetic energy of rotation—it is given by Eq. (19.8)...
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Question about finite difference Method for spherical potential

I don't get how to implement finit difference method for calculating energies in a finite,spherical well. Im frustrated and just changed everything multiple times. But nothing changes. [plot
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Is capacitance dependent or independent of potential?

The capacity of a conductor is independent of the charge given or its potential raised. However, my textbook states: The principle of a capacitance is based on the fact that capacitance can be ...
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Potential Difference in Electromagnetic Induction

Is $\int E \cdot \text{d}s$ for a branch having non-zero current $I$ and resistance $R$ equal to $IR$ if the current is induced by varying magnetic field?
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How can there be two potentials at this point?

In this potentiometer configuration, The blue circled junction has potentials $V$ and $E$ at the same time (Galvanometer shows no deflection), Why is this so? What conceptual error have I made?
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Potential at a distance $y$ from centre of a uniformly charged disc [closed]

Here, I have attached my try work below. Though I am stuck in integration, but I would like some physics people to answer it. Can I treat the $y\sin\theta$ factor to be constant while doing ...
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What means “A grounded conductor has potential equal zero”?

When I have a force field $\boldsymbol{\vec{F}}$ it tells me how the momentum of the particle will change given in a position on space. When we talk about an electric field $\boldsymbol{\vec{E}} = \...
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If potential at centre of a uniformly volume charged cube (side $a$) is $V⁰$, what is potential at its corner? [closed]

If potential at centre of a uniformly volume charged cube is V⁰, what is potential at its corner? Through internet, I came to knew that answer is V⁰/2, but everywhere it has been answered logically by ...
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(geometric) Does an eigenfunction necessarily tends to infinity in regions where time - invariant potential is greater than energy?

A diatomic-like setup: There are 3 regions: $x < x', x \in [x', x''], x > x''$ with potential being $V\left(x\right) > E$, $V\left(x\right) < E$ and $V\left(x\right) > E$, respectively, ...
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Is the electric potential same everywhere in a shell where electrons revolve?

The shell in which the electron revolves, is that an equipotential surface because the electron revolves with constant speed, so it means that there is no change in kinetic energy and hence no work is ...
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Tunneling in Infinite potential well [duplicate]

In quantum mechanical tunneling particle doesn't scale the potential but instead find a short route to cross barrier. Then why is tunneling only possible in case of finite square well potential and ...
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How does charge redistribution occur?

Consider 2 concentric thin hollow conducting shells with charges $q,2q$ and radii $r,2r$ for simplicity. If I attach a conducting wire between the 2 shells, then how would the charges now be ...
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Is current directly or inversely proportional to potential difference? [duplicate]

Ohm's law states that current flowing in a conductor is directly proportional to the potential difference applied across it's ends provided that physical conditions and temperature of the conductor ...
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Constancy of Wronskian when potential has Finite Discontinuities

I am working on a problem where for the 1-dimensional Hamiltonian $\hat{H}=(-1/2m)(d^2/dx^2)+\mathcal{W}(x)$ with $\mathcal{W}$ assumed to be smooth and real and $\Psi$ as solution to $\hat{H}\Psi=E\...
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What is the gravitational potential of a homogeneous sphere? [closed]

I am studying gravitational potentials from the book Galactic Dynamics by James Binney and Scott Tremaine. They provide the equation from where the potential of a spherical system is to be derived as: ...
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Why do we use high resistance wire in potentiometer?

I was recently learning about potentiometer and , my teacher told thta potentiometer wire has very high resistance , but if potentiometer wire has very high resistance , wont the current skip ...

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