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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Why are Electric Fields an exact differential?

{E - Electric Field Vector ; x^2 - x raised to the power 2} When finding the Potential Difference between two points in a non uniform electric field, the equation of $E $ given in the question is ...
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Confusion about magnetic vector potential

I'm confused about two things : the illustration and the "vector" in magnetic field . I didn't understand why the potential created by magnetic field got vector . I know about Helmholtz theorem , but ...
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How do the formula of electrostatic energy change from vacuum to with matter?

I know that, in vacuum, the electrostic energy is: $$ U_E = \frac12 \int \rho(\mathbf r)\varphi(\mathbf r) d^3\mathbf{r} $$ But I don't know how to pass to the matter version? The formula would be ...
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Can the energy of a charged ring have some sense?

I know that the density and potential (in spherycals) of a charged ring is, respectively,: $$ \rho(\textbf{r}) = \frac{\lambda}{a} \delta(r-a)\delta(\theta-\tfrac{\pi}{2}) $$ $$ \varphi(\textbf{r})= ...
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Voltage and Resistance definition

Consider a wire of lenght $L$ and transversal area $A$ that it isn't an ideal conductor, but follows Ohm's Law. After a few computations we have $$-\Delta\phi = \rho\frac{L}{A} I $$ where $\rho$ is ...
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The motion of a particle through a capacitor

I'm stuck trying to find an equation for the position of a particle travelling through a capacitor, however the capacitor gives an electric field that changes direction the further you get into the ...
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Charge a metal by applying potential

I don't understand why if we apply a potential to a metal it can attract electrons. An example of this is an electron gun, the anode is at a positive potential and its function is to attract the ...
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How to get Airy differential equation?

A particle with mass m is under the following potential: $$V(x) = \begin{align} 0 |x|\leq L ; c(|x|-L) |x|>L \end{align}$$ and the schrodinger equation: $$ \psi (x)'' + \frac {2m}{\hbar^2} ...
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No current through equipotential surfaces

While solving some simple capacitor problems, I found that certain "excess" capacitors could be removed from a circuit if they're connected across equipotential wires (especially in case of ...
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Differential Equations in a Discharging RC Circuit in Parallel

Please consider the following RC circuit as context: Assume that the circuit has been connected for a long time. If switch S has been opened at $t=0,$ the differential equation used to solve for the ...
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Line integral of a point charge

I am trying to teach myself Electrodynamics through self-study of Griffiths' Introduction to Electrodynamics, and I am having difficulty with a calculation that involves a line integral of a point ...
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Particle moving in Morse potential

I'm solving for a particle moving in the Morse's potential $$ H=\frac{p^2}{2m}+A\left( e^{-2\alpha x}-2e^{-\alpha x}\right) $$ Now, considering an operator $B=-\partial_x +C e^{-\alpha x}-D$ and its ...
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What is the possible arrangement that requires the minimum number of capacitors? [closed]

My textbook says the following: An electrical technician requires a capacitance of 2uF in a circuit across a potential difference of 1kV. A large number of 1uF capacitors are available to him each of ...
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Is “Particle in a box” actually a misnomer?

In the usual statement of the Particle in a Box problem, we assume two infinite potential barriers, to hold its wavefunction constrained, so it goes to zero on both ends: But instead of invoking some ...
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Origin of the definition of the electric potential of a black hole

All the papers I’ve seen in black hole thermodynamics (e.g. arXiv:hep-th/9908022) define the electrostatic potential of a black hole with horizon Killing vector $\xi^a$ as $$\Phi := \xi^a A_a \big|_{...
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Finding electric Field and potential [closed]

A non-conducting semi circular disc (as shown in figure) has a uniform surface charge density σ. The ratio of electric field to electric potential at the centre of the disc will be I tried it but am ...
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Direction of vector magnetic potential

I was reading the Feynman lecture about vector magnetic potential and I have a doubt about it. For a certain example it is written that: We have, then, a general method for finding the magnetic ...
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How to obtain large order perturbation series for cubic anharmonic oscillator?

Consider the potential $$V(x)= \frac{x^2}{2} + gx^3.\tag{1}$$ Then the time-independent Schrödinger equation becomes $$\left(-\frac{1}{2}\frac{d^2}{dx^2} + \frac{x^2}{2} + gx^3 \right)\psi = E(g) \...
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Does potential energy of a charge gradually decrease when it moves from a higher potential level to low potential level?

I have read that the analogy of gravitational field is similar to electric potential energy..now if I have a ball falling from higher potential level to lower potential level,then the potential energy ...
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Does the potential gradually decrease as we move from higher potential level to lower potential level of acell [closed]

Does the potential gradually decrease as we move from higher potential level to lower potential level of acell through a conductor or It just remains the same throughout
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What causes the charges in conductor to move towards lower potential terminal of cell [duplicate]

Whenever a conductor is connected to a cell,what causes the conventional positivecharges inside it to move towards the lower potential level of cell.. My question is whether the charges experience a ...
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How does Cell mechanism transfer charges against potential difference

In case of a cell,the positive charges (conventionally)move from Higher potential to lower potential..but how actually it happens when charges reach to lower potential terminal of cell ,whether cell ...
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Current flows without any potential difference [duplicate]

why current if flowing if there is no potential difference. if no potential difference then no work is being done on charge so there should be no net displacement of charge but we know that the ...
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Is the potential at each point on a circuit same? [duplicate]

Is the potential at each point on a circuit same,if so why? I have read that in order for current to flow through any kind of resistance,the potential of charges reaching resistance is higher than ...
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Retarded potential fields and gravity simulations?

Dear physics stack exchange, I've been trying to consider exactly how to program a gravitational simulation with time-retarded gravitational potential fields. Its proven difficult given each time one ...
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What is the energy transformation that occurs when a ball rolls down a suspended ramp and then fall down? [duplicate]

I'm trying to finish my physics project and I'm trying to describe the energy transformations. If a ball rolls on an ramp (suspended on a wall) and then falls - is there kinetic energy to gravity ...
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Electric Potential of a sphere concentric to a spherical shell [closed]

The sphere with radius a, is concentric to the spherical shell with inner radius b and outer radius c. The charges are distributed uniformly in volume. b) Find the electric potential in region outside ...
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How do the electric field lines distribute inside a current carrying conductor?

We know that when we connect a conductor to a source of potential difference, an electric field is established inside the conductor. With the help of calculations which I show below, we can see that ...
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Force through potential energy: does the absolute value of energy has sense?

Force can be found from potential energy: $$\vec{F}=-\nabla U$$ In other words, force depends on how the potential energy changes in space, but not on the potential energy value? Or if we take ...
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Doubt concerning force on a charged ball

There is a problem I am trying to solve where I am facing certain doubts. Here is the question: A metal ball of radius 5 cm is given a charge of 100 esu. Find the force acting on it per unit area. ...
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Electric field and current

When we provide a potential difference in a circuit it does nothing more than provide an electric field to the conductor,When an electric field is provided in a conductor the free electrons move to ...
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Why do photoelectrons from a vacuum photocell move towards the collector plate if it is not charged? Has it been charged beforehand?

Why do photoelectrons from a vacuum photocell move towards the collector plate if it is not charged? Has it been charged beforehand, or do they simply move forwards because of the kinetic energy they ...
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Potential function for conservative internal forces

In Goldstein's Classical Mechanics book, he considered a system of particles and looked at the conservative internal force between particle $i$ and particle $j$ that satisfy the strong law of action ...
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Difference between thermodynamic potentials and free energy

Reading this post, How can one say that if we subtract "TS" from "U" then what we get is free energy? I read that: Strictly speaking, free energy is the difference in the value ...
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System of $N$ conductors: Coeficients of Potential derivation

First of all, I have read this question and didn't found an answer. I think the notation I will use (the one my professor used) is the same used in the Reitz/Milford. Unfortunately, my Reitz version ...
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Why are there electric field lines outside the conductor but not inside?

The Electric field at point P (for an electric slab) is given by $E_P=\frac{\sigma}{\epsilon_0}$, however, since $E$ inside the metallic slab is zero, the electric field at point P is contributed by ...
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Why does Flow always occur from Higher Potential to Lower Potential?

This is a sort of a generalized question and not just referring to the flow of current. This includes fluids and many other such entities. But why does this flow occur. For example if I consider ...
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Potential drops across resistors

Similar questions have been asked here, but there's one part of this that I don't understand; in a resistor connected in a circuit, as the energy of the electrons decreases when they pass through the ...
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Potentials in a MOSFET [migrated]

My knowledge is very basic. For this question I consider n-channel enhancement mode MOSFET. I see some MOSFETs have 3 terminals, while others have 4 terminals. This forth terminal is the base ...
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Capacitor between two equipotential surfaces [closed]

Is a capacitor possible between two equipotential surfaces? I asked my teacher and the explanation given was: There is an electric field between the two equipotential surfaces, thus energy is stored ...
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Confusion between positive and negative terminals of a battery

I am confused that whether the positive terminal in physics refers just to a higher potential or a positive charge. This also comes from the fact that anode and cathode are differently charged in ...
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A question about electric potential

I want to ask about the interpretation of electric potential as it relates to this simple problem : " "A $0.800$ mm diameter ball bearing has $1.50 \times 10^9$ excess electrons. What is the ball ...
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Is there any way to get a different current (apart from $\frac{V}{R}$) across a resistor with a specified potential difference between it?

My question is originally from an youtube video, which is a tutorial series on digital electronics. In a nutshell, He (the one in the video) has a predesigned input signal which fluctuates the ...
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Two charged spheres connected by a wire

I have a few doubts about this problem. So we have two charged spheres of radius $r_1$ and $r_2$, one is initially charged with a charge $Q$, while the other one is initially without charge. The ...
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2 points of same potential in a single circuit [duplicate]

Can we just say that if between 2 points in some given circuit, there's no load, then the potential at those 2 points are same?
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Potential at infinity and zero of an infinitley long Cylinder with dirichlet boundary conditions

I have an ifinitley long cylinder in z direction with the boundary condition $\phi(\rho=R,z,\varphi)=\phi_0+\phi_1 \cdot \cos(v\varphi)$ or $\phi(\rho=R,z,\varphi)=cos(kz)(\phi_0+\phi_1 \cdot \cos(v\...
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Electric Dipole inside a cavity of conducting sphere [closed]

In the problem, a cavity is taken out of a uniform conducting sphere. Inside the cavity, a dipole is placed as shown in the fig. find the potential at point P
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Do all conservative forces act in the direction of decreasing potential energy?

Let us take two unlike point charges $q_1$(positive charge) and $q_2$(negative charge). When we decrease the distance between them, the potential energy between them also decreases according to the ...
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Confusion In Concept of Equipotential Surface

I have recently come across this topic of equipotential surfaces. I have a very basic doubt: Q.) Let's say we are talking about a point P inside the equipotential surface(eg:sphere). Now, before ...
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Direction of Current Flow in Circuit with Multiple Cells

As the point $A$ is earthed we know that its potential is zero, same is true for point $B$. Due to the cell between $B$ and $C$ we can say that potential at $C$ is $-3V$. So the potential at point D ...

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