# All Questions

327 questions
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### Potential in open branch of a parallel circuit with grounding [closed]

If the switch is still open, what will the electric potential at Q be, i.e. negative, positive or zero? Is there a potential difference across the grounded point and point Q, or R3, even though the ...
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### Particle in a box plus step (ground state)

I am trying to come up with a QM problem that: Can be solved analytically Contains a potential that is a sum of some analytically solvable potential and another contribution: $V'=V_0 + V$ Is then ...
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### Sphere half-submerged on a dielectric

This is a classic problem in electrostatics with a twist, so I thought it could be useful for others here. I did have a problem with the integration at the end, but on general I think the idea can ...
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### Energy formula for finite potential well [closed]

The energy formula for infinite potential well is $$E=\frac{n^2h^2}{8ma^2},$$where $m$ is the mass of the particle, $a$ is the width of the well but in the case of finite potential well, I actually ...
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### Confusion about Change in Integration Variable [closed]

I'm working through example 3.2 of Zangwill's Modern Electrodynamics and have come across a change in integration variables that I just can't seem to get. The example has two different change ...
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### Understanding conformal mapping in electrostatics

I'm trying to understand the use of conformal mapping to solve problems in electrostatics. To better understand the idea, I'm trying to learn how to solve this example (but you can propose any other ...
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### Calculation of Gravitational Potential at the centre of the cube [closed]

I came across this problem in a test and have been able to come up with a solution however I am unsure if it is correct. I started by building a cube of twice the initial dimensions to bring point P ...
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### Does gravity get stronger when you climb a mountain?

As stated in the question title, what happens to the strength of the gravitational field (or equivalently, your weight) as you climb a hill or mountain? Would a weighing scale show that you were ...
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### Determining Electric Potential due to a line of nonuniform charge density [closed]

A rod of length $L$ lies along the x axis with its left end at the origin. It has a non uniform charge density $\lambda = \alpha x$ where $\alpha$ is a positive constant. Calculate the electric ...
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### Can electric potential be discontinuous?

I am studying the following problem, which is 9.11 of "Modern Electrodynamics" by Zangwill. The idea is that you have a wire attached to a perfectly conducting sphere (radius $a$) buried into the ...
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### How do we deduce the vector potential for a constant magnetic field?

How do we show that for a constant magnetic field $\vec B = const$, the vector potential is $\vec A = \frac12 \vec r \times \vec B$?
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### Given the parameters of the electrostatics problem, is this integral possible to evaluate analytically? [closed]

A cone with apex at the origin has a height $h$ and a top radius $h$, a uniform charge density with no charge on the top face. I need to find the potential $V$ at a position $z$ on the cone's axis ...
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### Power series solution for a shifted spherical harmonic oscillator

I'm trying to solve the Schrodinger equation for a radial Harmonic oscillator whos equilibrium point has been shifted away from the origin, i.e. $V(r) = V_0(r-1)^2$. The standard approach is to make ...
218 views

### Fourier tranform of Coulomb-like potential $1/|r-r'|$

I've found that Fourier transform of Coulomb potential $V= q/r$ is $F[V]= 4\pi q/k^2$. Now I need to calculate fourier transform of function $1/|r-r'|$. And I exactly don't know how to operate with ...
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### Electric potential - Batygin, Toptygin book

I found in Batygin and Toptygin problems in electrodynamics a particular problem: Density of charge is $$\rho = \rho_{0}\cos{\alpha x} \cos{\beta y} \cos{\gamma z}$$ in whole space. Find electric ...
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### Introducing stream function with given velocity equation

Bit information about the problem We are dealing with the slide coating process - where basically a polymer is being put onto a slot, which is moving in the $x$-direction with velocity $v_0$. The ...
197 views

### Electric Potential of Non-Uniformly Charged Infinite Plane

A little background: I was tutoring an undergrad upperclassman when we came to a problem that he had been assigned which I couldn't make heads or tails of - at least in terms of what was being ...
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### Parallel voltage source concept

I am having doubt understanding this: If two voltage sources V1 and V2 are connected in parallel with different voltages like 2v and 3v is it possible or the scenario is wrong. An example is this ...
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### Electrostatic Potential of a Hollow sphere [closed]

When calculating the electric potential inside the hollow portion why are we adding all the electric potentials of the previous cases??? Instead when calculating for other cases i.e the cases before ...
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### Obtaining Components of the Vector Potential [closed]

I am given $\boldsymbol A(r,\phi) = \frac{i}{e}a(r)U(\phi)\nabla U^{\dagger}(\phi)$, where $U(\phi)=e^{in\phi}$. I want to obtain the magnetic field $\boldsymbol B$ from this vector potential, so ...
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### Which test function (under variational method of approximation) should be used for a linear potential?

There is this problem, it is not for evaluation, I mean, it is not homework. There is a 3-dimension potential $V(r)=C . r$, where $r$ is the radial coordinate and $C$ is a real constant (I think it ...
I am trying to analyze a particle in a box with a rather strange potential inside the box: $V(x) \propto x^{3/2}$ I've tried using the WKB approximation, but I get some strange results and I don't ...