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 [tag:magnetic-...

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Will Coulomb law work if both the charges are moving with same speed and same direction?

I read it on wikipidia that Coulomb law will work if both the charges are at rest relatively. Will there be an effect of magnetic field also?
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2answers
326 views

Why is the potential energy of a dipole in an electric field zero when the dipole points perpendicularly to the field?

I have read that potential energy of a dipole in an electric field is taken to be zero at 90 degree as they say that it is a reference. But there must be some reason behind it?
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1answer
133 views

Gauss law example - Electric field and dA [duplicate]

I am still very confused and lost. I still dont understand why E1 is pointing down , E3 and 2 pointing up. while dA is point the left and dA2 and dA3 are in the same direction of the E3 and E2. I ...
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1answer
36 views

Gauss law question with regard to this example

I am really confused in Gauss law. Why do E3 and E2 pointing up? and also E1 pointing down? The lecture note said infer from symmetry and you will get the following but I dont really understand. ...
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1answer
37 views

Gauss Law Question [duplicate]

Why is ${\rm d}\vec{A}_1$ pointing up and ${\rm d}\vec{A}_2$ pointing down? Electric field ${\rm d}\vec{E}_1$ is pointing up so isn't it supposed to be perpendicular to the surface?
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153 views

Chapter 26 Electric Fields Physics 212

A very long sheet of charge has width $L$ and surface density $n$. The sheet lies in the $xy$ plane between $x=-\frac{L}{2}$ to $x=\frac{L}{2}$ and $y=-\infty$ to $y=\infty$. Where the radius is $r=x -...
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2answers
35 views

Finding Charge given Electric Field

This question came up in a competition, and I didn't know how to solve it. ABCD is a rectangle with width $2d$ and height $d$. At point D, there is a charge with magnitude $q_1$ At point B, there ...
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1answer
39 views

The electric field created by a uniform charge density

Given the electric field defined by: $$\vec {E(\vec r)}= x \hat {x} $$ There is no obvious contradiction with the classic electro-magnetic theory. But: $$\vec \nabla \cdot \vec E = 4 \pi \rho(\vec r) =...
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1answer
19 views

What are the potentials of a battery with respect to earth?

Assume an open-circuit voltaic cell. We know that the cell maintains a potential difference between its terminals. That is $V_+ - V_- = E$. Now, if I connect $(-)$ to earth using the earth terminal ...
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2answers
74 views

Gauss Law Question. Could anyone explain to me why does S3 is 0 in this lecture note example?

Why does S3 equal to 0 ? for E3 dot dA = 0? Could I also know why does dA1 and dA2 point up and down? while dA3 point to the right?
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2answers
415 views

Maximum limit of charging a capacitor

We say that we can charge a capacitor in proportion to the potential difference we apply across its plates and the maximum potential difference depends on the dielectric strength of the medium. Now ...
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1answer
111 views

Can I create a static electricity water magnet?

I came to watch a video that water dipole get attracted by static electricity. I wanted to know if I could make a static electricity device that could pull out all the water from a wet cloth.
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32 views

Determining the Potential of a Loop with a Given Line Charge?

I am trying to determine the potential at a point $P$ for a loop consisting of two quarter circles, one with a given radius of $a$, and the other with a given radius of $2a$. There is a line charge on ...
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0answers
29 views

Does a Description with Photons as Force Carriers Apply for Non-Radiative Systems?

What is the full quantum mechanical description of the statement from classical electromagnetism "the electric field of a uniformly charged infinite flat plane is constant"? By "full" I mean that I'm ...
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2answers
332 views

HOW is electric field inside a conductor placed in an external field zero?

Lets assume that there is an external field +E acting on a conducting plate from left to right. Due to this, some electrons will drift from right to left to cancel out this electric field inside the ...
2
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1answer
82 views

Balloon and Static Electrcity

I am learning about charge, but there is one thing I don't understand. In the above picture, I understand that the balloon sticks to the wall because of the attraction between the negative charge ...
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1answer
113 views

What does electrically charged mean?

So I was reading my physics textbook and it said that "Suppose we have two metal spheres, one highly charged and the other electrically neutral." What does it mean by highly charged? Does that mean ...
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1answer
37 views

Why a capacitor's potential increase until it is equal to the potential of the battery?

I understand that the potential between the plates of the capacitor increases as the circuit runs, but why it stops increasing exactly when it becomes equal to the potential of the battery?
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2answers
371 views

Potential at the center of a cubical box

Problem 3.16 from "Introduction to Electrodynamics" by D. J. Griffiths. Five sides of a cube are at zero potential. One remaining side (insulated from others) is at potential $V_0$. What is the ...
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1answer
207 views

Method of image charge for cylindrical conductor

I am simply puzzled that only for spherical and planar conducting surfaces the method of images is applied. Is it (really) impossible to find image charge or charge distribution which can simulate the ...
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1answer
41 views

The electric field inside the shell [closed]

If we place a $+q$ charge in the center of a spherical shell, what is the electric field inside the shell?
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4answers
183 views

Why is the total potential difference in a circuit the sum of the individual potential differences?

I am having difficulty in applying my understanding of electrical potential to circuits. Why is the total potential difference in a circuit the sum of the individual potential differences among ...
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1answer
202 views

How can an electroscope measure voltage?

An Electroscope consists of a lightweight, conducting needle hinged to a conducting pole. If the pole is charged, the needle will deflect from its zero-point because it is charged the same way as the ...
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3answers
307 views

Difference between $E$ field configuration, sheet of charge: infinite sheet of charge, conducting vs. non-conducting

This is a very easy question, but I often confused myself. Perhaps someone could explain this concept again: A non-conducting infinite sheet of charge has the electric field configuration \begin{...
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2answers
130 views

How is the differential form of Gauss Law used?

How is the differential form of Gauss's Law $\mathbf{\nabla}\cdot{\bf E} = \dfrac{ρ}{ɛ}$ used? What I mean is, where am I measuring $E$ and what is $ρ$ in this context?
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1answer
74 views

Does charged saltwater repel itself?

if you take a volume of saltwater, and charge it to a high voltage, will the water molecules repel each other and climb the walls of the container slightly, or does the fact that water is polar ...
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1answer
33 views

Potential on a uniform

My doubt is in the part where he sets $V=V_s - \int{E dr}$. My idea is that he is summing two potentials, from the surface, and the one he's trying to calculate with the integral. Is that right? If so:...
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1answer
467 views

What is the difference between an electric field and gravitational field? [duplicate]

Since the electrostatic field and the Newtonian gravitational field share a similar form: proportional to $$ \frac{1}{r^2} $$ Is there any qualitative difference between motions under the ...
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0answers
117 views

charge flow between a sphere (inside) a spherical shell irrespective of the charge of the shell

a small sphere of radius r1 and charge q1 is enclosed by a spherical shell of radius r2 and charge q2.If q1 is +ve charge .Then , charges will flow from sphere to shell ,when the two r connected by ...
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0answers
50 views

The torque $\bf p \times \bf E$ on a dipole causes it to oscillate about $\bf E .$

The torque $p \times E$ on a dipole causes it to oscillate about $\bf E.$ Only if there is dissipative mechanism, $y$? Why does it not work without it?
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1answer
70 views

Does magnetic induction produce potential across zero resistance wire?

If magnetic field is increased at a constant rate inside a zero resistance wire loop, then, according to Faraday's law , $$\varepsilon = \frac{dΦ}{dt} $$ Thus, a potential difference is produced. ...
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2answers
152 views

Flux of electric field through a closed surface with no charge inside? [duplicate]

I'm reading the Feynman lectures on electromagnetism and in Vol II, Chapter 1.4 Vol. II, Chapter 1-4 he talks about the flux of the electric field and says that flux of $E$ through and closed surface ...
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1answer
70 views

Why can't a compact 10 MeV electrostatic particle accelerator not be built?

I've been thinking about this problem for a while, since I want to see if a compact accelerator driven nuclear reactor can be built for powering aircraft and rockets. The reaction I am considering for ...
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1answer
43 views

What would the $\nabla^2 V $ be at the border of a conductor?

We are studying laplace's and Poisson's equation for electrostatics in my class. It was cursorily said that $\nabla^2 V = \sigma / \epsilon_o $ at the surface of the conductor. This makes no sense as ...
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2answers
555 views

Gauss' law in differential form for a point charge

I'm trying to understand how the integral form is derived from the differential form of Gauss' law. I have several issues: 1) The law states that $ \nabla\cdot E=\frac{1}{\epsilon 0}\rho$, but when ...
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1answer
56 views

Effect of introducing an external charge beside a Gaussian surface

As far as I know, Gaussian surface's are surfaces that enclose a net charge and are shaped in such a way that the electric field vector's magnitude is the same over the entirety of the surface. My ...
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1answer
245 views

How charges can be at rest if there is a force on it?

Electrostatics deals with forces between charges at rest. But if there is a force on a charge, how can it be at rest? My guess is that charges is being kept at rest by some unspecified forces that ...
2
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2answers
472 views

What is Gauss's Law in two dimensions?

I am trying to figure out how the equation for the field if a Gaussian surface was applied to a 2D plane. I did see another question already asked on the subject, but I didn't get a particular ...
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0answers
99 views

Relationship between electric field and distance

I am working on a lab report that asks a conceptual question related to one of the labs we did on electrostatic fields. For the context of my question, here is how the experiment is set up. We have ...
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1answer
187 views

Why isn't energy stored in a capacitor equal to just $QV$ when it is fully charged? [duplicate]

I just learned that the energy stored in a capacitor is electrostatic potential energy. Also potential energy is a state function and is independent of the path. So, when the capacitor is fully ...
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1answer
68 views

Calculating the rate of electrostatic discharge via current density

After I asked this question, with the help of Floris' comment, I tried to learn more about the concept of current density and tried to calculate the current density in my scenerio which, it seems, is ...
3
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1answer
215 views

Calculation of long-range forces in Molecular Dynamics - Ewald summation

I am trying to write a code to calculate the potential and forces, for the same using ewald summation.For this purpose, the formula for potential and force I have used is : $$ U = U^{(r)} + U^{(k)} +...
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0answers
91 views

Derivation Electric force

I’m a physics of high school (SMAN 3 Bandar Lampung, Lampung, Indonesia 35116). I make the experimental apparatus in static electric field. Instrument arrangement in the image below: The theoretical ...
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2answers
415 views

When I take a Gaussian surface inside an insulating solid sphere, why does the outer volume have no effect on the electric field?

Say I try to find the magnitude of the electric field at any point within an insulating solid sphere. I know that in the case of a conductor, the electric field within it is 0. However, I have not ...
2
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1answer
67 views

EMF produced when a square wire is pulled from the corners [closed]

The shown diagram is of a square conducting frame being pulled from the corners. The velocity of A and B is given as $u$. Each side has length $a$. I was trying to find the induced emf at the instant ...
0
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0answers
29 views

How does air neutralize charged objects? [duplicate]

How exactly does air neutralize charged objects? For example, at what rate does air neutralize a copper sphere of radius R and net charge Q? I assume that the rate may vary depending on the surface ...
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1answer
58 views

In a Wimshurst machine, why are the Leyden jars connected?

I generally understand how Wimshurst machines and Leyden jars work, but I can't figure out why the outside of the two Leyden jars in a Wimshurst machine are connected to each other. The DIY guide I've ...
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1answer
105 views

Help me understand Gauss law

Suppose I have the following, the gaussian surface is the drawing in the middle. So charge enclosed is zero, and then eletric field must be zero since the area of the gaussian surface is not zero. But,...
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0answers
37 views

Eletric field on a slab, uniform volume charge density

These are the question and the solution in solutions manual. However, I don't understand the step in which he goes from $\rho V/A$ to $\rho \Delta x$.
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0answers
57 views

Can you calculate the charge after rubbing two objects

If there are two insulators and you rub them together for a long time, is there a way to calculate how much charge should have transferred between them. I'm sure there is some relation to the ...