Scalar and vector potentials in electromagnetism. The scalar potential is potential energy per unit charge. For potential energy, use the potential-energy tag.

learn more… | top users | synonyms (1)

-2
votes
0answers
27 views

Can someone explain me magnetic potential?

I don't understand why we can write the magnetic field as a potential vector A, and what exactly this potential is. Is it just a mathematical thing? And how can it help me calculate the magnetic ...
0
votes
1answer
33 views

How to Explain the the following situation?

I have thought a simple thing: consider a system of a planet and its natural satellite revolving around it in a perfectly circular orbit(assumed) and this is happening in an isolated space in some ...
0
votes
0answers
36 views

Schrödinger Equation (with finite potential outside well) [on hold]

Derive the eigenvalue conditions of the eigenenergy values of the bound states of a particle of mass m in a one-dimensional potential well. $V(x)=\begin{cases} -V_0 ~&\text{for}& ...
5
votes
2answers
774 views

Degeneracy in one dimension

I'm reading this wikipedia article and I'm trying to understand the proof under "Degeneracy in One Dimension". Here's what it says: Considering a one-dimensional quantum system in a potential ...
1
vote
2answers
150 views

The Zero Electric Potential of the “Earth”

I know its the potential differences that matter and generally we define the zero of the electric potential according to our convenience. I would like you to look at this standard problem: Charge ...
0
votes
0answers
23 views

Electric potential due to something

What is the diffrence between "electric potential at some point due something" and "electric potential of something" ?
1
vote
0answers
33 views

Determine potential function given initial conditions?

Assuming a radially symmetric circular disk (let's say r=1). Given two simple initial conditions: Potential at the centre is 4 V Potential at the edges is 0 V How would I determine the potential ...
0
votes
2answers
33 views

Why electric potential at equatorial point of a dipole is 0?

Well ok I know that electric potential at equatorial point of a dipole is 0. It is a derived conclusion. Q1. But how this can be explained "theoretically"? Another question that electric potential ...
3
votes
1answer
120 views

What does a voltmeter actually measure?

For time varying fields (even quasistatic ones) the electric field is given by $${\bf E} = - \nabla \Phi - \frac{\partial {\bf A}}{\partial t}$$ So what does a voltmeter measure? Does it measure a ...
0
votes
1answer
112 views

What's my $\mathrm dM$? Gravitational Potential inside a circle of mass

I'm trying to find the gravitational potential for an arbitrary point within a ring of uniform mass density. The point is constrained to be in the same plane as the ring. So we start with: ...
8
votes
2answers
557 views

Why do we use gauges in Maxwell equation?

While solving the Maxwell's equation we often use the Lorenz or Coulomb gauge, but why is that? Are the equations unsolvable if the gauge is not fixed? Or is it just for the simplicity?
0
votes
1answer
41 views

Infinite depth potential well (energy probability) [closed]

Consider a particle in an infinite depth potential well of length 2a. The particle is in a state in which it is described by the wavefunction $\psi (x)=A(a^2-x^2)$ for $-a\leq x \leq a$ with a ...
2
votes
2answers
151 views

Scalar and Vector Potential

I am a physics undergraduate student currently studying electromagnetics. I have previously studied electrostatics and magnetostatics yet the concept of scalar potential, $V$ and the vector potential, ...
-2
votes
1answer
16 views

Which of these values has larger gravitational potential? [closed]

As an example: $-65\ \mathrm{MJ/kg}$ or $-20\ \mathrm{MJ/kg}$? I understand that all gravitational potential energy is negative, and that obviously the larger value is $-20$, however I don't know if ...
0
votes
1answer
24 views

why does the Lennard-Jones potential fail to accurately describe forces between simple molecules, eg ammonia?

I have found only one reason, this being polarisation isn't accounted for. See for example this PDF - it is in the middle of the second paragraph, first page. What other reasons lead to the failure ...
1
vote
1answer
66 views

Under what condition is angular momentum conserved in both classical and quantum physics?

Classically, angular momentum is only conserved in a central potential by considering the torque (correct me if I am wrong). In quantum mechanics, it is also true, isn't it? If this is the case, ...
0
votes
0answers
20 views

Grounding system of conducting plates

So, I always make mistakes on problems such as this (the grounding part), so I'm hoping someone could really explain to me how the process works . There are n large parallel plate conductors carrying ...
0
votes
1answer
21 views

Charging capacity and capacitance of a conductor

I know that charging capacity of a conductor is the maximum charge a conductor can hold And capacitance is the ability of a conductor to hold charge in a given potential . But how are these two ...
0
votes
1answer
27 views

Why is resting membrane potential or a membrane depolarisation localised to the membrane?

Why would a membrane depolarisation be localised to one part of the membrane? If adjacent areas have a more negative potential shouldn't the difference in potential cause charge to flow into the ...
1
vote
2answers
48 views

Why is the electric potential zero in this case?

The situation: a charge of $-2q$ is situated a distance $r$ to the left of a charge of $q$. What is the electric potential at a point $p$ a distance $r$ to the right of charge $q$? So basically: -2q ...
0
votes
1answer
195 views

Explain confinement energy for a particle in a box

What is a "particle in a box"? How does confinement energy equal kinetic energy? How does confinement energy relate to the spectrum energy (the absortion/emission between energy)?
0
votes
1answer
30 views

What does potential mean in capacitor?

Technically potential means work done to move a unit positive charge from one point to another against electrical field but What does potential mean in a capacitor?
1
vote
1answer
508 views

Induced electric field due to a moving wire

An infinite wire carrying a constant current $I$ in the $\hat{z}$ direction is moving in the $$y$$ direction at a constant speed $v$. Find the electric field, in the quasistatic approximation, at the ...
1
vote
3answers
531 views

How the electric potential of a charged body depends on the surface area of the body?

I have studied in the book that electric potential of a body depend on the surface area of the body, that is as the surface area increases potential decreases keeping the charge as constant and vice ...
3
votes
1answer
51 views

WKB Approximation on an linear + harmonic potential

I have a quick question: I have performed the WKB approximation to find the energies of bound states in symmetric potentials (Square, harmonic, ...). To do this I just find the "turning points" by ...
0
votes
0answers
19 views

Which is the form of Born-Mayer repulsion term?

I have found in many textbooks different and unclear form of the Born-Mayer repulsion term. I write the interatomic potential as $V(r)= -\frac{e^2}{r}+V_{BM}$ and for $V_{BM}$ I expected something ...
0
votes
1answer
19 views

De-merits of the application of Laplace's Equation to find electrostatics potentials

QUESTION: What are the de-merits of the application of Laplace's Equation to find electrostatics potentials? Our professor told us that the answer was as follows: It can be used only when the ...
4
votes
2answers
93 views

What happens to the electric field at the boundary of a dielectric?

The question in the title is a broader one, but for now, I want to confine myself to the following problem. I have the task to find the potential difference between points A and B shown in the ...
-1
votes
0answers
32 views

Why both fuse and earthing ???' [migrated]

This question arose in my mind today that when you already have the fuse for safety precautions why do you need the earthing?
0
votes
2answers
35 views

Measuring potential

I apologize if the question below has been asked -- I could not find an answer. A charged conductor some distance above ground generates an electric field and corresponding potential profile. How ...
0
votes
1answer
36 views

Resistance from $I$-$V$ graph

I thought that the answer was obviously A as the gradient remains constant...however, the answer is B...who so?
0
votes
3answers
36 views

EMF or terminal voltage?

I have a doubt that is: What does this statement mean: "a 6 V battery". Does this mean that the EMF of the battery is 6 V or the terminal voltage of the battery is 6 V? If the battery has internal ...
2
votes
1answer
142 views

Introducing cut-off in a renormalisation procedure for quantum mechanics

I've been reading a paper on renormalisation theory as applied to a simple one-particle Coulombic system with a short-range potential. In the process of renormalisation, the authors introduce an ...
-1
votes
0answers
21 views

Doubts wrt Electromotive force

The definition of emf states that when a cell is in open circuit , the potential difference between the terminals of the cell is called the emf. Now i dont understand that how can p.d. be taken into ...
0
votes
0answers
55 views

Finding $\psi(0)$ using Schrodinger equation with potential $U(x) = q\delta(x)$

I am having some trouble answering the following question in my "Advanced Quantum Mechanics" course: Using the integral equation: $$\psi(x) = Ae^{ikx} + Be^{-ikx} - ...
0
votes
0answers
15 views

Where is the zero electric potential energy point?

Does the point of the electric potential energy of zero is defined by human or dominated by the indefinite integral of the electric force?
1
vote
1answer
39 views

Why is the energy shift due to a 'sagging' potential negative and independent of box size?

Consider a box of width $L$ and the composed of the following potential $$V(x)=\frac{V_0x(x-L)}{L^2}, x\in[0,L]$$ and $V(x)=\infty$ elsewhere. Using perturbation theory - with a square box as the ...
0
votes
0answers
23 views

Charge Magnitude Based on Isoline Spacing

Suppose we have two positive charges of unknown magnitudes. We are given the isoline map (the equipotential lines) for the two-charge system. One has isolines more "squashed together" (more closely ...
7
votes
1answer
883 views

Child-Langmuir space charge law for non-zero cathode potential (non-zero initial electron velocity)

I'm trying to reconcile some conflicting results that I've found in publications that address the idea of the current in a vacuum diode in the case where the cathode has a non-zero potential, in other ...
2
votes
0answers
41 views

What is the charge density for line and surface charges?

In electrostatics it is common to see line, surface and volumetric charges being described differently. A line distribution is a function defined on the line, a surface charge distribution is a ...
0
votes
1answer
268 views

Semi-infinite / Asymmetric potential well

I'm asked to come up with an ansatz and solve for the coefficients of a asymmetric infinite potential well, where: $$ V = \begin{cases} \infty \text{ for } x< 0 \\ V_0 \text{ for } 0 \leq x \leq L ...
0
votes
1answer
183 views

What is a Hulten potential?

What is the Hulten potential? (also spelled Hulthén, Hulthen, and Hultén.) When is it used? How is it derived? I vaguely heard about in the context of neutron synthesis / quantum mechanics.
0
votes
0answers
30 views

What is the relationship between potential energy and electrical potential?

I actually always thought this was trivial, now I am not so sure. For a potential $\phi$ the potential energy is $V=q\phi$ where q is a test charge. Now I am thinking this may work differently in two ...
-4
votes
1answer
131 views

If systems minimize their potential energy, why do people climb mountains?

A person climbs a mountain. They convert the stored chemical energy of food in their body and back pack into heat energy on the mountain, and gravitational potential energy as they move towards the ...
0
votes
1answer
33 views

Understanding electric potential in the context of gravitational potential?

I'm trying to understand the concept of electric potential and the significance of an electric field being related to the gradient/derivative of an electric potential. I found this question that ...
0
votes
1answer
159 views

How can energy be negative in a finite square well?

Say if the potential $V(x) < 0$ in the well but the sides or the scattered states its zero potential, anyways How is that the energy in the well is less than zero? Is it because the potential ...
0
votes
0answers
37 views

What is the difference between length and velocity gauge when it comes to a dipole approximation?

Lets say we have plane wave with $\vec E$ perpendicular to $\vec k$. The dipole term will come from $\vec A\cdot \vec p$. Is the electric field longitudinal in the length gauge for the dipole ...
-1
votes
2answers
36 views

I don't get the idea of potential in a capacitor [closed]

First off, what is meant by the potential of the conductors? Also potential difference between the two conductors is a function of distance from either right? Then why does it have an exact value. For ...
2
votes
4answers
594 views

Dipole in a spherical cavity in an infinite dielectric

In this example the assumption is made that inside a spherical cavity (with an infinite dielectric) with a dipole placed at its centre, the potential takes the following form: $$\phi_{in}= \frac{p ...
1
vote
4answers
6k views

Potential difference between point on surface and point on axis of uniformly charged cylinder

Question: Charge is uniformly distributed with charge density $ρ$ inside a very long cylinder of radius $R$. Find the potential difference between the surface and the axis of the cylinder. Express ...