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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Checking for equilibrium in a square configuration of charges [closed]

Four equal positive charges each of magnitude q are placed at the respective vertices of a square of side length l. A point Q is placed at the centre of the square. Then find the state of equilibrium ...
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1answer
127 views

What is the force between two charged objects when the space between them is partially filled by a dielectric medium?

I am given two charged particles of same charge at a distance of $r$. They initially apply force $F$. Now an infinite dielectric (of dielectric constant $4$) of width $\frac{r}{2}$ is introduced ...
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0answers
20 views

What is the electrostatic force between charges if they separated by a combination of dielectric media? [duplicate]

How does the combination of different medium affect the force? How do we calculate the equivalent dielectric constant? Say, two charges are separated by 100 cm, first 10 cm is a slab of dielectric ...
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1answer
37 views

The force on the northern hemisphere

I am reading Griffiths' Introduction to Electrodynamics. On page 364, example 8.2 (4th edition), he calculates the force on the northern hemisphere of a ball with total charge $Q$ spread uniformly. ...
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1answer
28 views

Induced electric field

Let's consider a thin cylinder of radius $r$ with a charge in is outer surface. It is made of an isolator. Let the magnetic field be parallel to its axis. If the magnetic field changed by $dB$ in time ...
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3answers
1k views

What types of materials can be electrically charged by rubbing?

What types of materials can be electrically charged by rubbing? Is there a certain type of materials in which static electricity can be produced by rubbing together two different materials?
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1answer
13 views

Displacement vector in parallel plate capactor

This ought to be simple, but I'm running into some questions... Let's say we have a parallel plate cap with some linear homogeneous dielectric media between the plates. The plates are distance $a$ ...
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1answer
116 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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1answer
61 views

Computational physics using mathematica [closed]

So I was confused about this question on how to exactly begin to answer it. I am a novice in mathematica and I am teaching myself thus I require help in this question. From what I think I should do, ...
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1answer
65 views

Potential of a uniformly charged hollow sphere [closed]

If I use Gauss' theorem I find that, for $r\geq R$ $$V(r) = \frac{\sigma R^2}{\epsilon_0 r} = \frac{Q_{sphere}}{4\pi\epsilon_0r}$$ where $\sigma$ is the surface charge density and $R$ the radius of ...
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1answer
78 views

Charge present at the centroid of equilateral triangle

Three equal charges +Q each are placed on the vertices of an equilateral triangle. A charge +q is initially placed at the centre of the triangle. If this charge (+q) is slightly displaced towards a ...
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2answers
73 views

Obtaining electric field of an uniformly charged sphere surface without using gauss law [closed]

How can i obtain the electric field due to a uniformly charged sphere surface without using gauss law on a point outside the sphere, im stuck not knowing what infinitesimal surface i shall consider so ...
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1answer
135 views

How to calculate the force between line of charges?

As far as I know Coulomb's law only works for point charges but what if there are not any point charges? For example, let's imagine there are three rectangles with different sizes. First one is 50 cm, ...
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2answers
59 views

Will the electrostatic force between two charges change if we place a metal plate between them?

If a thin metal plate is placed between two charges $+q$ and $+q$, will this cause a change in the electrostatic force acting on one charge due to another? What is the concept behind this? What will ...
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0answers
21 views

Accurateness of measurement of 1Ampère for the last years, especially depending from the method how to switch on the current?

From Wikipedia: Ampère's force law states that there is an attractive or repulsive force between two parallel wires carrying an electric current. This force is used in the formal definition of the ...
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1answer
2k views

How is capacitance of a cylindrical capacitor calculated?

I've just begun learning capacitance, and my lecture notes have a section on calculating capacitance for capacitors in vacuum of various shapes, e.g. two parallel plates and concentric spherical ...
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2answers
33 views

Electrical breakdown due to a charge

Electrical breakdown occurs due to the fact that the magnitude of electric field of a charged object is above the electrical breakdown limit of the insulator that surrounds the charged object. ...
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1answer
721 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
827 views

How can I find the potential created by spherical capacitor with dielectric material?

If we have a spherical capacitor with inner radius or r1 and outer radius of r2, with charges (+/-)q on them and there is a dielectric material (with constant e) in between them with. What kind of a ...
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1answer
32 views

How does the magnetic field generated from a rectangular cross-sectional current-carrying conductor differ from a circular cross-sectional conductor?

I can find much information of cylindrical conductors (ie. regular wires), where $B=\frac{\mu_0 i}{2 \pi r}$ and $r$ represents the radius (or distance) from the centre of the conductor, however I ...
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2answers
38 views

Why can't electric potential be negative?

As a general concept, potential energy of a configuration is equal to the work done by an external force against an existing conservative force. It is this work done that gets stored in the body as ...
2
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2answers
147 views

Electric force between charges in two different media

As far as I know, Coulomb's law of electrostatic force is applicable on two different charges situated in same medium. But if two individual charges are in different media (say one charge on a iron ...
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0answers
13 views

Coulombian force when the 2 charges are in different mediums [duplicate]

2 charged particles are kept at a distance r. The mutual force of attraction/repulsion is F. What happens to the force when only one charge is kept in dielectric medium (k) other is in vacuum
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1answer
35 views

Potential in uniform fields

First in a book I found that the electric field strength $\mathrm{E}$ of a uniform electric field from a charged plate is equal to $\frac{q}{2\times \epsilon_0 \times S}$ where $q$ is the charge of ...
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1answer
95 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
46 views

Why am I getting that work it's always the same in both directions?

I'm studying electrostatic and I'm getting pretty frustrated because with the definition of work I'm getting that it's always positive and it doesn't make any sense. So here I have 2 positive ...
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1answer
21 views

Could you give boundary conditions to the gravitational potential given the density distribution?

We´re doing a project that's all about solving differential equations with separation of variables. We´re trying to find the gravitational potential given the density distribution (that has azimuthal ...
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0answers
15 views

Electric field inside a conductor placed in uniform electric field

When a conductor, with a cavity containing a charged species, is kept in uniform electric field, will any change to the external electric field result in a change in the internal electric field inside ...
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1answer
25 views

Why does the molar conductivity decrease with increasing charge density?

This is a question in a problem sheet I have been set. Is it do do with the following equation: $\Lambda=\Lambda_0-a\sqrt c$? Surely charge density is proportional to concentration so therefore molar ...
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1answer
31 views

Uniform Electric Field

I was going through the first chapter in Resnick Halliday related to electromagnetism and then I came across something called a uniform electric field. It was written that "If E is uniform (that is, ...
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1answer
29 views

Electrostatics and tv screens

My physics textbook states an activity- "Cut out thin strips of paper and lightly iron them. Take them near a TV screen or computer monitor. The strips get attracted to the screen and may cling to the ...
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0answers
11 views

Why does a field-effect transistor with wrap-around gate work at all?

In the recent years several publications have presented field-effect transistors (FETs) that are based on semiconductor nanowires with a gate electrode that is wrapped around the whole nanowire ...
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3answers
114 views

Electric potential energy and signs

I know that electric potential is negative near a negative charge and positive near a positive charge. But does this mean a small positive 'test' charge has a negative electric potential energy near a ...
2
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1answer
135 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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2answers
105 views

How does electrostatic force affect electronic devices?

How does electrostatic force generated by two seperate plates having opposite charges affect electronic devices? I know that magnetic fields have some harmful effects to electronic devices but I am ...
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2answers
34 views

Electric Field At Centre Of Non Uniform Ring

In the above solved example why only the cos components have been taken for calculation of electric field at centre ? Why not the sine components ? BTW in case you say that the sine components ...
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1answer
49 views

Why can we ignore self energy?

I have been doing some practice questions in a text book [Electricity and Magnetism by Purcell and Morin]. So I know that the energy the potential energy of a system is the total work required to ...
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1answer
511 views

Dielectric slab counter-intuitive formula?

For the calculation of force on one of the two equal(in magnitude, opposite in sign) point charges separated by $r$ with a dielectric slab of dielectric constant $K$ and width $d$ in between, the ...
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0answers
20 views

Does a negative and a positive charged body repel vs. attract a suspended negative charged ball with the same strength?

In this question I'm in trouble about my statement, that the measurement instrument does not influence the electron's electric field. It seems to me that only the repelling force between negatively ...
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0answers
20 views

Is the electron's magnetic dipole moment influenced by the measurement method?

The electric charge of an electron at rest is a constant value and is not influenced by the measurement instrument. The measurement instrument by itself can give more or less accurate result, but does ...
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1answer
38 views

Find out gradient of electric potential at ${\bf r}$ created by eletric dipole of moment ${\bf p}$ [closed]

Suposing an electric dipole of moment ${\bf p}$ located at the origin which creates an electric potential at ${\bf r}$ given by ...
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6answers
6k views

Workdone in an equipotential surface is zero?

An equipotential surface is one in which all the points are at the same electric potential. If a charge is to be moved between any two points (say from point A to point B) on an equipotential surface, ...
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1answer
37 views

Description of charged sphere with Heaviside function in cylindrical coordinates

I need to describe density of charge of uniformly charged sphere (radius R, total charge Q, position of centre (0,0,0)) with Dirac delta function and Heaviside step function. The hard part is to ...
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1answer
43 views

The Electric Quadrupole

I've read the following sentence: "Every electric circuit with two pairs of accessible terminals is called a quadrupole." I was wondering why does it happen that the multipole expansion gives us a ...
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1answer
37 views

Electric Dipole force exerted by a charged wire on a dipole

Why is force exerted by a charged wire on a dipole given as $F = P×(dE(r))/(dr)$ where P is the dipole moment? Please explain in simple words and avoid using too much technical derivations.I am a ...
1
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1answer
257 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 ...
4
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2answers
64 views

Does the electric force on a charged particle in a uniform electric field increase?

If I have a proton in a uniform field between two parallel oppositely charged plates and the proton accelerates, the electric force acting on it stays constant seeing it is a uniform field and as a ...
2
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1answer
29 views

Electric field in space created by intersection of spheres of charge

I am trying to calculate the electric field in space created by a body assembled by the intersection of 2 spheres. The upper sphere, its center is at $\frac{d}{2}\mathbf{\hat{z}}$ with radius $R$ and ...
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1answer
68 views

Wait… why exactly does farady's ice pail experiment prove Gauss's law?

You'll notice there are no equations in this: that's because this is a question of morale, not of math. But a humble one at that! I come to learn, not to expound. But don't let that limit the form ...
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1answer
27 views

How can a cable pass signal

I am currently study electrostatics. And I don't get how can electrons pass signals in a cable, can somebody explain this to me specifically?(I am only twelve years old) Thank you very much!