Electrostatics is concerned with the electrical fields and scalar potentials of stationary electrical charges and charge distributions. Use this for questions about electromagnetic situations in which currents and magnetic fields are absent, otherwise use [tag:electromagnetism] and/or ...

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Electric field in a non-uniformly charged sheet

So if we have a large sheet that is not uniformly charged and is NOT a conductor, how can I find an expression for the electric field everywhere? Things we know about the sheet: the width is 2b it ...
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15 views

Finding the electric field of a NON uniform slab?

So if we have an infinite slab that is not uniformly charged and is NOT a conductor, how can I find an expression for the electric field everywhere? Here's a picture http://imgur.com/S9WzHir Things ...
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6 views

How will open-circuit voltage affect the Fermi Level Difference

The circumstances in which I am asking the question is a material A that is part of an open-circuit and in contact with a different material B. How would the open-circuit voltage affect the Fermi ...
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where has the energy gone when the test charge turned away?

Consider an insulated ball with some charge $q_1$ inside it.Now we take a small area over that ball uninsulated i.e we had cut a small portion. Now when we bring a test charge from infinity near that ...
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83 views

Capacitance of spherical capacitor when earthed

The capacitance of a spherical capacitor is given by $$C=\frac{4\pi \varepsilon_{0}}{\left ( \frac{1}{a}-\frac{1}{b} \right )}$$ How can I find out the capacitance of the capacitor when The ...
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279 views

Force due to combination of free space and dielectric

I will make a generalized form of my question. There are two point charges $q$, $x$ distance apart. And there is a dielectric slab of thickness $t$ and of dielectric constant $K$. Should the force ...
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1answer
22 views

Work Function Calculation with Local Electrostatic Potential

On the Wikipedia site, it describes the work function equation as W = -e\phi - Ef, where phi is the electrostatic potential of a vacuum nearby the surface of the material. So my question is, how can I ...
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3answers
130 views

How does the conductor knows which side is outside?

For a electrostatic equilibrium state, we know charges only stay on the outer surface of the conductor. But, how does the conductor know which side is outside? If it's about the curvature, then ...
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1answer
39 views

Minima & maxima of Laplace's equation

I don't get the following sentence from David J. Griffiths' Introduction to Electrodynamics (the ambiguous sentence is in bold) Laplace's equation tolerates no local maxima or minima; extreme ...
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1answer
233 views

Simulate / plot electrostatic field

I have something like this: For given voltage (9 V red wire, 0 V blue wire) I want to simulate electrostatic field. I already know, for example that in the point (10.5;0) there are 10 V and etc. I ...
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If we charge a capacitor can we discharge it into a battery?

I have read that we can charge a capacitor using a battery, but can the vice versa happen? My project needs to show a battery being charged through a fully charged capacitor.
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Capacitance of a single charged plate?

Lets say we have a single plate that has a charge of +Q on it. A plate with charge -Q is infinite distance away. Will the plate with +Q have a capacitance associated with it? Why or why not? I was ...
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3answers
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Zero current induced in a loop

Consider the following two cases, Case 1 – A coil moving through a constant magnetic field Case 2 – A conductor moving through a constant magnetic field Now, in Case 1 (a coil moving through a ...
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97 views

Electric Potential Energy

When work is done on a positive test charge by an external force to move it from one location to another, does the potential energy increases or decreases, and does the electric potential increases or ...
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1answer
20 views

variation of electrostatic potential on moving radially outwards from the nucleus of an atom

I was wondering how would the electrostatic potential change on moving radially outwards from the nucleus in an atom, considering the effect of the electron clouds around it.
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1answer
224 views

How to find the electric field of a charged tube?

Let's say there is a charged tube(cylinder with no top or bottom) with radius $a$, length $l$ and charge $q$ and a point which is collinear with the centre of the charged tube. Anyway, since we can ...
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22 views

Comparison of capacitances

The figure shows two arbitarily shaped surfaces S1 and S2.S1 is a thin metal foil, which has been slowly beaten to form the surface S2 without any loss of charge.. S2 lies completely within or on ...
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Difference between parallel and series capacitors

Basically, I can't figure out that whether a capacitor is connected in series or parallel. The same problem occurs while solving for resistors. Can someone help me understand this difference ...
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2answers
2k views

The electric field of a conductive sphere containing a charge - grounded vs not grounded

Let's suppose we have a sphere but unlike theoretical ones it'll have some thickness say $\Delta r$ and inner radius $R$. What I was wondering about is how will it behave if we place some charge $q$ ...
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45 views

When is work done on or by something?

An example, here what my textbook says: When charges are released In electric fields charges experience the force causing them to accelerate along electric field vectors. Positive charges ...
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Nucleus validation [duplicate]

Inside the nucleus of an atom is the Coulomb's law valid? I mean that between proton, neutron and other elementary particles, i.e., meson etc. What will be the limit or validity of charges between ...
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1answer
24 views

Electric Fields in a Neutral Object

A neutral object has no net charge since its positive and negative charges cancel each other. However, I’m wondering how, in terms of fields, they do cancel each other. Since fields are vectors, won’t ...
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2answers
594 views

Why electric field inside charged conductor is zero in the electrostatic case?

I am trying to understand the idea (or the fact) that most books introduce which is about the electric field inside a charged solid conductor Books tell that the field has to be zero everywhere ...
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14 views

Do Anodes Emit Virtual Photons Representing Their Positive Electrostatic Potential

I understand the electrons in circuit travel down the path of least resistance, however are electrons attracted by the emission of virtual photons emitted by a source with relatively low electron ...
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The Electrostatic-Potential Variable of the Work Function Without the Presence of a Vacuum [on hold]

In the Work Function Equation, the variable of the Electrostatic-Potential is described as the Electrostatic-Potential of a vacuum nearby the surface. However, how would this variable change if there ...
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3answers
449 views

Polarization vector of dielectric electrostatics

I know two laws for Polarization vector of a dielectric material $$\vec P = N q \vec{\Delta L}$$ Where $N$ is the number of dipoles per meter cube, $\vec{\Delta L}$ is the vector that represents the ...
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1answer
40 views

Electric field between capacitors [closed]

A parallel-plate capacitor consists of two parallel, conducting plates of area $A$, separated by a distance $d$. Each carries a charge of magnitude $Q$; positive on one, negative on the other. ...
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Why the magnitude, $E$, of the field vector is different for every sets of (parallel) plates?

This is quoted my textbook. I wonder why we can't reproduce the same magnitude on a different set of plates, if we make them the same size, same charge, and having the same electric potential, and ...
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2answers
38 views

Is this diagram in my textbook not constructed to scale?

Or am I having an illusion. Clearly, the distance from 6v to 4v is not the same as 4v to 2v. I know it should be based on: $V = k\frac{q}{r}$.
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40 views

What is the strength of the magnetic field required to penetrate an average human body?

Introduction Suppose you are an experimental nanobot researcher trial-ling a new form of medication that involves activation and control of nanobots within the cells of the interior of the human body ...
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1answer
48 views

Is the sea of electrons in a metal at rest when the metal is in electrostatic equilibrium?

It is said that charges inside a metal in electrostatic equilibrium are at rest, and are stationary. However, don’t the electrons have their own thermal vibrations and whatnot? Aren’t they always ...
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1answer
143 views

Static electricty and fields inside of the conductor?

I have a few related questions about static electricity and conductors. 1. when we say static electric field inside a conductor is zero, let us take an example of two concentric conductors, outer one ...
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1answer
34 views

Earnshaw's theorm and Effective potential

Earnshaw's theorm says "no stable equilibrium for any $\frac{1}{r}$ potential field in charge-free space". Now I am confused in some aspects, and I would like some helping hands. 1.)General physics ...
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4answers
219 views

Is Gauss' law valid for time-dependent electric fields?

The Maxwell's equation $\boldsymbol{\nabla}\cdot \textbf{E}(\textbf{r})=\frac{\rho(\textbf{r})}{\epsilon_0}$ is derived from the Gauss law in electrostatics (which is in turn derived from Coulomb's ...
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1answer
51 views

Why isn't the electric field zero in the empty space?

A spherical portion has been removed from solid sphere having a charge distributed uniformly in its volume the electric field inside the emptied space is? Isn't the electric field suppose to be zero ...
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1answer
41 views

Potentials of electrical multipoles vs strong interaction

Are there any reasons of the similarity? As I remember both potentials have the form $$\sim e^{-\alpha r}/r$$ where $r$ is the distance. The comment of Bort below led me to Wikipedia ...
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1answer
19 views

Why does power loss in pure metal caused by temperature is calculated base on $P=I^2R$ but not $\frac{U^2}{R}$

$$P=I^2R=\frac{U^2}{R}$$ The metal's resistivity is temperature dependent, neglect the change in size by temperature. The power loss of a pure metal when it drop form temperature $T_1$ to $T_2$ is ...
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3answers
7k views

Why does the area of the plates affect the capacitance?

Why does the area of the plates affect the capacitance? Lets say I have a parallel plate capacitor with a charge of 10C and a potential difference of 5V. By the definition $C=Q/V$, the capacitance is ...
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1answer
792 views

Electric field from conductive to dielectric media

I am interested in the main difference between transitions from electric fields from Conductive to Conductive/ Dielectric to Dielectric and Dielectric/Conductive media. What are the boundary ...
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3answers
93 views

Electrostatics and two electric charges

How can two identical metallic objects have the same but opposite charges (one loses electrons and one gains electrons) when we know that metals have the ability to lose electrons only?
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2answers
214 views

How do electrons distribute themselves along a wire attached to one pole of a battery?

Let's assume we have an electrochemical cell, like an AA battery. We attach a long straight wire to the negative terminus of the battery, the other end of the wire extends right away from the battery ...
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35 views

Electric Potential Between Two Like Charges

At the point horizontally across and equidistant from the centers of the two charges (also oriented horizontally), what is the electric potential? At that point, the electric field of the first charge ...
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116 views

Help understanding the solution to a problem regarding kinetic energy of a group of point charges

The problem provided by my professor goes as follows: "Now consider a situation in which all charges are equal to q and they simultaneously become "unglued". What speed will each charge have when a ...
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2answers
41 views

Do permanent magnets have an electric current surrounding them?

Permanent magnets seems to have different properties to electromagnets, such that electromagnets can be used for induction and energy transfer if a conductor is placed within their changing magnetic ...
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9 views

Measuring Charge Density

I am running tests with metal electrodes and I am trying to find a value for charge density which I can use in calculations. If I have two vertical electrodes across which I am applying a voltage, how ...
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1answer
16 views

Zero of Electric Potential Energy

When you have a positive charge and a negative charge, the line that cuts perpendicularly between their separation distance is an equipotential line of 0 volts. The math indicates that at that point, ...
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2answers
142 views

Two capacitor plates with equal positive charges $q$

I read in a book that if both the plates of a parallel plate capacitor are given equal positive charges $q$, then the charges on the facing surfaces will be zero and the charge on the outer surfaces ...
3
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1answer
49 views

Interpretation of a term in the Maxwell stress tensor

With no magnetism, the $xx$ component of the Maxwell stress tensor $T$ is $$T_{xx} = \frac{1}{2}(E_x^2 - E_y^2 - E_z^2)$$ I can see why there should be a $+E_x^2$ term, but intuitively I don't see why ...
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Electic potential due to finite rectangular plate

I am trying to find the potential at any point (x,y,z) due to a rectangular plate with a constant surface charge density. Let's assume the plate is centered on the X-Y plane and extends from -n to n ...