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.

1,565 questions
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Conductance Charged Box

A box with thick and conductive sides with dimensions: Lx, Ly, Lz- while LZ>>Lx,Ly. The long dimension of the box [Lz] can be viewed as infinite so Phi(x,y,z)=Phi(x,y) Given that: Phi(0,y)=-Phi(Lx,...
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How do you derive a wave function?

I know this may be a dumb question to ask, but I'm a middle school student studying quantum physics out of interest and want to know how to find the wave function. Preferably in a square well.
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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 ...
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Converting from magnetic scalar potential to magnetic vector potential

Suppose that I have a situation where I can use the magnetic scalar potential. Given the magnetic scalar potential, is there a simple way to calculate the magnetic vector potential from the magnetic ...
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Fixing the potential for a quantum particle

I have started studying quantum mechanics and have realised that we can solve the Schrodinger equation for a particle's wave function if we know it's potential energy function. But the potential field ...
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Curl of gradient of potential in electrostatic

We know, curl of E is zero (this field is conservative). Again E=-grad V. So, we get curl of (-grad V)=0, i.e. curl of gradient of potential is zero. Is there any condition on potential?
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Finite potential well; finding the energy “in a limit”

I've come a across the following variant of the finite-potential-well-problem in quantum mechanics: The potential is given by $V(x)=0$ for $|x| \geq a/2$ and $V(x)=-V_0/a$ for $-a/2<x<a/2$ where ...
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Barrier Potential for bound states

I'm having this problem for a while, but I'm still failing to realize what really is bothering me in this, so here is my attempt on explaining my doubt: I have the time-independent Schrodinger ...
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Is magnetic potential vector due to the magnetic field or energy stored in magnetic field?

My doubt is whether the magnetic vector potential is due to the potential energy stored in magnetic field or due to the magnetic field. Also I have another doubt. Since in electrostatics potential ...
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Resistors equivalent using symmetry and equipotential line

I propose the following statement: In a circuit, while determining equivalent resistance across two points, if the circuit is symmetric wrt the line joining the two points , we may fold the circuit ...
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Trying to understand the electric potential and potential energy

I am trying to understand some facts on electrical potential and potential energy. It is quite confusing in the text to say that the zero potential could be freely chosen for convenience. In that case,...
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Potential difference between two electrodes in an electrochemical cell

In an electrochemical cell, let's say you have a zinc and zinc ion half-cell as well as a copper and copper ion half-cell: The zinc electrode (or anode) dissolves into zinc ions while the copper ions ...
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Is the scalar magnetic potential continuos?

If we have two current-free spaces and separated by a surface current, we can solve the magnetic problem by solving two magnetic scalar potentials and then using matching conditions. My question is, ...
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Direction of $d\mathbf{l}$

A solid sphere has charge $q$ and radius $R$. Find the potential at a point a distance $r$ from the center of the sphere where $r>R$, using infinity as the reference point. My attempt: From Gauss'...
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Laplace equation outside sphere

When solving the Laplace equation on sphere coordinates you get: $$u(r,\theta) = \sum_{n=0}^{\infty}\left( A_n\,r^n + \frac{B_n}{r^{n+1}} \right) P_n(\cos\theta)$$ And it is clear that if you have ...
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Electric potential in circuits

From what I understand from my notes, an e.m.f or electromotive force provided by a battery is the electrical energy per unit charge converted from other forms of energy required to drive a unit ...
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Electric Potential in the Center of a Electric Dipole

I thought the electric potential at point B would be positive because placing a positive charge at point B would cause it to move releasing energy while doing so. The answer key states that the ...
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What is the electric field between two coaxial conducting cylinders when a charged sphere is placed within the inner cylinder?

A long cylindrical capacitor of length $l$ consists of an outer conductor of radius $a$ and an inner conductor of radius $b$, where $l>>a$. The outer conductor is earthed, and the inner ...
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Can EMF be lesser than terminal potential difference?

Can terminal potential difference be greater than EMF? If so, how? Upto my knowledge and my research, during charging it can happen but the question remains same: how it happens. What is the basic ...
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Electric potential due to a current source - Basic equations

In my book I found the folowing formula of the electric potential generated by a current source: $$\Phi = \frac{I}{4 \pi \sigma} \frac{1}{r}$$ where I is the current, $\sigma$ the electrical ...
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Ideal/Non ideal Voltmeter across a battery with no current flowing

If I consider a voltmeter and connect it across a battery , which is in such a circuit , that no current is flowing in that branch (Before Voltmeter is connected), will the voltmeter, show the EMF of ...
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Understanding bound states in quantum mechanics

Suppose I have this potential: $$\ V(x)= \left\{ \begin{array}{ll} +\infty & x < 0 \\ -V_0 & 0\leq x\leq a\\ 0 & x>a \\ \end{array} \right. \$$ for $a>0$...
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Equipotentiality of the conductor surface with extra charges sprinkled and Poisson's equation

The electrostatic potential $\phi(x,y,z)$ everywhere on the surface of a conductor/metal is the same. For a quick reference see this post. Hence, any derivative of $\phi(x,y,z)$ must be zero on the ...
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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 ...
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Why electric potential requires absence of acceleration?

As of 28/05/2019, Electric Potential is defined in Wikipedia in the article with the same name as: The amount of work needed to move a unit of positive charge from a reference point to a specific ...
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Form of the one-pion exchange potential

Part of the one pion exchange potential (OPEP) contains the following term $$V(r) \propto (\vec{\sigma}^{(1)} . \nabla)(\vec{\sigma}^{(2)} . \nabla) \frac{\exp\left(- \frac{r}{R}\right)}{r}$$ And I ...
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Deriving energy eigenfunctions of Infinite square well with nonzero bound

I've been asked to derive the eigenfunctions for the infinite square well, but by using boundaries of $L/2$ and $-L/2$ instead of $0$ and $L$ I'm happy with the general solution found using the TISE ...
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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 ...
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How to take the derivative of potential?

The electric potential $\psi$ at a point inside the volume charge distribution is: $$\displaystyle \psi = \lim\limits_{\delta \to 0} \int_{V'-\delta} \rho'\ \dfrac{1}{|\mathbf{r}-\mathbf{r'}|} dV'.$$ ...
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Taking into consideration the non-0 value of an equipotential in a method of images problem

If the infinite conducting plane in the diagram above is grounded, then $V=0$ on the plane and the image problem is easy to solve - just put the dotted $-q$ charge there and the $V=0$ equipotential ...
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How can you use the potential to find the electric field? [closed]

Lets say we have the above system of point charges. We were asked to find the electric field at the centre. Superposition of electric fields gives the right answer, but how can we do it by ...
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What is the equation of the gravitational potential in general relativity?

How is the gravitational potential replaced by the metric tensor in general relativity? $$U_G=\frac {GMm}{r}$$ What is its equation?
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Even and odd solutions to time independent Schrodinger equation on symmetric potential

I have to solve the following problem: Consider the potential well: $$V(x)=-V_0, \hspace{10px} |x|<a/2$$ and $0$ everywhere else. $a$ is also a positive constant and so is $V_0$. Find the ...
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Is electric potential just the sum or measure of Electric Potential Energy for a given unit of matter with electric change?

I understand Electric Potential as follows (I "synthesized" the definition from different definitions I found online): The sum of Electric Potential Energy for a matter particle with an electric ...
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Why is $E=-dV/dx$?

I know Work= minus Electric Potential Energy. So you have: -qdV=-qE dx and thus E= minus dV/dx. But does that 'minus' sign have any effect so E vector's direction. Say we have the fields lines (red)...
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Why does a voltaic cell induce an electric force proportional to voltage?

I'm trying to understand the intuition behind Ohm's law (that current is proportional to voltage). I understand the basics of the Drude model: if the electrons frequently collide and on average reset ...
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Understanding Charge Density when using Laplace's Equation

I'm following Griffith's Intro to Electrodynamics, and when discussing Laplace's Equation, it states Very often we are interested in finding the potential in a region where $\rho = 0$. So, if you ...
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Showing $\nabla \cdot \mathbf A = 0$ using integral formula

In Coulomb gauge the vector potential is chosen so that $\nabla \cdot \mathbf A = 0$ and we find $$\nabla^2 \mathbf{A}=-\mu_0 \mathbf j$$ The solution to which is  \mathbf A(r) = \frac{\mu_0}{4\...
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Is a complete circuit required for capacitors to redistribute charges?

Suppose I have two capacitors of different capacitance $C_1$, $C_2$and they have been charged prior connecting by voltage of $V_1$ and $V_2$ respectively the positive plate of one capacitor is ...
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Connecting one lead of capacitor to a certain charged object (to get a potential difference)

Setup-A charged sphere , connected to one plate of capacitor , other lead of capacitor is free. Question-Will the capacitor plates go through a charge redistribution ? Arguments/Counterarguments-I ...
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Work done in moving a charge in circuit?

Why is the work done in moving a charge from one point to another in a circuit through any path the same even though heat and other losses are there?
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How one can use the Klein-Gordon equation to deal with the hydrogen atom? [closed]

I'm not familiar with physics jargons compare to those who study physics professionally, but to remark my knowledge regarding this question, the Klein-Gordon equation is a relativisitc equation for ...
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How do you measure voltage from first principles? [closed]

I've always wondered if you were thrown back in time with just my cell phone, how could I charge it... I know how to make electricity, but how do I check the voltage if all I have access to is, shall ...
Why the electric field on the surface of charged spherical shell of radius $R$ and charge $q$ is $\frac{kq}{R^2}$?
As we know the electric field at a point due to charge $q$ is equal to $\frac{kq}{r^2}$ where $k$ is the constant of proportionality and $r$ is the distance between the charge and the point (where we ...