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.

Filter by
Sorted by
Tagged with
0
votes
0answers
17 views

Help verifying Schrodinger's Equations for regions with different potentials

This problem is 1-dimensional along the z-axis. For z<0, V=0. For 0d, the potential is zero once more. I am working under two principles 1)whenever a wave is incident on some discontinuity, some ...
0
votes
0answers
24 views

Can A Potential Function Have Maximum And Minimum In Free Space ? Why? [on hold]

Can A Potential Function Have Maximum And Minimum In Free Space ? Why ?
0
votes
1answer
30 views

Potential drop across inductors in DC circuits

The potential drop across an inductor is equal to $L(di/dt)$ where $L$ is inductance coefficient. But according to this in a DC circuit there should be no potential drop across the inductor (because $...
2
votes
3answers
51 views

Electric potential and drift speed of electrons through circuit

What I have since learned: (Tell me If I am wrong) In circuits ,Batteries provide electric potential difference (voltage) ,This difference creates electric field (Over the conductor or the wire) ...
2
votes
1answer
48 views

Potential - When and when not to use infinity as a reference point?

I'm reading Griffiths' Electrodynamics and having a bit of a problem to understand when we can use infinity as a reference point and when it cannot be used. One question asked to calculate the ...
0
votes
1answer
32 views

Schrodinger equation: If $V(x)=V(-x)$ then prove that $\psi(x)=\psi(-x) $ or $\psi(x)=-\psi(-x)$ [duplicate]

The title explains itself. If the potential is an even function then prove that wave function is either odd or even. I set $-x$ in Schrodinger equation and find out that $\psi(-x)$ is also a solution ...
1
vote
1answer
61 views

Time for a particle to reach the centre of a potential on a straight path [on hold]

I'm working on a problem in classical mechanics. We have a particle moving in a potential $V=\frac{-a}{r^n}$ where $a$ and $n$ are given constants. Now we let go of the particle at the position $r(t=...
0
votes
1answer
34 views

Forces inside battery

The title itself seems silly to me but here is this question, A constant electric force of $8\ \text{N}$ acts in the direction shown and constant non electric force of $10\ \text{N}$ acts rightward, ...
0
votes
2answers
153 views

Compact expression of Maxwell's equations: missed minus sign

With much courtesy I ask a simple explanation to be able to obtain a minus sign missing from the compact form of Maxwell's equations: $$\boxed{\square \overleftrightarrow F=\mu_0 \boldsymbol{\mathcal{...
0
votes
0answers
34 views

Stationary State of Quantum Mechanics [duplicate]

Why for every normalized solution to the time-independent Schrödinger equation $E$ must exceed the minimum value of $V(x)$?
-2
votes
0answers
35 views

Is there a minimum energy in the ground state of a particle in a finite square potential well? If yes then how to find it? [closed]

The equation can be given as: $\phi(x)=Ae^{\gamma x}$ for $x<-\frac {L} {2}$ $$\phi(x)=A \frac{e^{-\frac { \gamma L} {2}}}{\cos\left(\frac{kL}{2}\right)}\cos (kx)$$ for -$\frac {L}{2}<x< \...
0
votes
0answers
38 views

Two dielectrics and one charge (image problem) [on hold]

There are two regions: A dielectric with permittivity $ \epsilon_2$ in the region $ z>0$ A dielectric with permittivity $\epsilon_1$ in the region $ z<0$ And a charge $q$ is situated at $(0,...
0
votes
0answers
21 views

Integrating to find the potential above a disc with uniform surface charge [closed]

Hey I'm solving this problem problem in Griffiths ED book. It is the 2.25th problem. Problem 2.25 Using Eqs. 2.27 and 2.30, find the potential at a distance $\:z\:$ above the center of the charge ...
1
vote
1answer
151 views
+50

Dielectric above and below the xy plane

This is problem 4.25 from Griffiths' electrodynamics, it says: Suppose the region above the $xy$ plane is filled with linear dielectric of susceptibility $\chi_e{}'$ , and the region below the $xy$ ...
0
votes
1answer
26 views

Heating a ball tied to a string so that its potential energy decreases as Center of mass goes down

Suppose I have a ball hanging from a thread and I start heating it. The ball is tied from the upper end and as the ball starts to heat it expands and ultimately its centre of mass which is the centre ...
0
votes
1answer
22 views

On electric potential and corresponding formulae

Why is it that signed quantities of charge are used in determining electric potential but not electric force (by Coulomb’s law)?
0
votes
2answers
47 views

What is the fundamental reason behind electric potential decreasing in the direction of increasing electric field? Is there any exception to this?

Does this increase and decrease necessarily have to be linear in nature? I have seen this statement being thrown around which states that in direction of increasing electric field the potential ...
3
votes
2answers
79 views

Velocity-Dependent Potential and Helmholtz Identities

I'm currently working through the book Heisenberg's Quantum Mechanics (Razavy, 2010), and am reading the chapter on classical mechanics. I'm interested in part of their derivative of a generalized ...
0
votes
1answer
20 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 ...
0
votes
1answer
46 views

Potential of a non uniformly charged spherical shell

This question is taken from The Feynman Lectures on electromagnetism. A spherical shell with surface charge density $\sigma = \sigma_0 \cos \theta$ is given. The potential at any external point is ...
0
votes
1answer
28 views

Electric potential energy in a system

According to my notes, electric potential energy of a charge at a point is the work done in bringing a charge from infinity to that point. So say, two electrons are brought from a point that's far ...
1
vote
0answers
29 views

Interpretation of induced force between two Dirac delta potential wells

This problem is based on MIT OCW course 8.04 problem set 6 question 5(e). https://ocw.mit.edu/courses/physics/8-04-quantum-physics-i-spring-2013/assignments/MIT8_04S13_ps6.pdf Consider two Dirac ...
0
votes
1answer
54 views

What is electric field vector? [closed]

What is electric field vector? How to find out the Electric Field vector at a point on a equipotential surface. Please explain by giving an example.
0
votes
0answers
53 views

How to find the charge distribution of a conducting disc?

Generally,Poisson's equation can be solved with appropriate boundary conditions to get potential from which the surface charge densities can be obtained. Most textbooks on Classical electrodynamics ...
0
votes
0answers
30 views

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,...
0
votes
0answers
90 views

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.
0
votes
1answer
37 views

Electric potential / infinity is not the 0 reference

Let's say we have a charged sphere with radius $r$. Usually, the way we define its potential is $V = kQ/r$. In this way, we have defined its potential with infinity as the zero reference point. Let's ...
0
votes
1answer
54 views

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 ...
1
vote
0answers
26 views

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 ...
0
votes
1answer
29 views

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 ...
0
votes
1answer
22 views

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 ...
1
vote
2answers
38 views

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 ...
1
vote
1answer
41 views

Condition for finitely many bound states in one dimension

This came up in the context of the inverse scattering transform for the KdV equation. My primary reference, a set of lecture notes on integrable systems by Maciej Dunajski, makes the claim that the ...
0
votes
3answers
41 views

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 ...
0
votes
0answers
22 views

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 ...
0
votes
0answers
25 views

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 ...
0
votes
1answer
50 views

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 ...
0
votes
2answers
28 views

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 ...
2
votes
3answers
108 views

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 $a>0$...
0
votes
2answers
28 views

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 ...
1
vote
1answer
36 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 ...
0
votes
1answer
72 views

How to take the derivative of potential?

The electric potential $\psi$ at a point inside the volume charge distribution is: $$\displaystyle \psi = \lim\limits_{\delta \to 0} \int_{V'-\delta} \rho'\ \dfrac{1}{|\mathbf{r}-\mathbf{r'}|} dV'.$$ ...
0
votes
1answer
18 views

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 ...
-1
votes
3answers
64 views

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 ...
3
votes
7answers
419 views

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 ...
0
votes
1answer
41 views

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 ...
1
vote
1answer
50 views

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\...
1
vote
2answers
100 views

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 ...
0
votes
0answers
27 views

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 ...
1
vote
3answers
74 views

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 ...