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Questions tagged [electrostatics]

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 the [electromagnetism] and/or [magnetic-fields] tags.

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Determination of null point in a field with more than two charges [closed]

To determine the null point of two like charges is to find the point where the net electric force is zero. However, when it comes to three charges with two like charges and one unlike charge, or five ...
Emmanuel_III's user avatar
1 vote
3 answers
83 views

Do conductors have bound charges?

In Griffiths, the total charge density of a dielectric is: $\rho$ =$\rho_b +\rho_f$. I have several questions: Can the total charge density of a conductor be written as the equation above? Do the ...
Felix wong's user avatar
2 votes
1 answer
29 views

Energy in Dielectric Medium as a Sea of Dipoles

Simply, why is the energy density in a dielectric medium = $\frac{1}{2}K\epsilon_oE^2$ where K is the dielectric constant of the dielectric medium? Working proof Consider a capacitor that is charged ...
Kayen Jain's user avatar
-1 votes
0 answers
16 views

Parallel plate capacitors with dielectrics [closed]

I was studying capacitors with dielectrics ,where my teacher gave one example for us to solve between the parallel plate capacitor there is dielectric which is further divided into four dielectrics ,...
Kushagra Mishra's user avatar
6 votes
1 answer
132 views

How to avoid the ordinary Coulomb solution in QCD?

To see where QCD starts to differ from the behavior of EM fields, we might begin by looking at the classical field. A search brings up [question 339978] and [question 360061] but no answer is found ...
Jos Bergervoet's user avatar
0 votes
1 answer
62 views

Electric field experienced by a charge

We have two charges, say $Q_1$ and $Q_2$. The magnitude of the electric field $E$ experienced by charge $Q_2$ is: $$E = \frac{k Q_1}{r^2}$$ where $k$ is Coulomb's constant and $r$ is the distance ...
user134613's user avatar
-1 votes
1 answer
24 views

Find Velocities When Distance is Minimal - Electrostatics [closed]

Introduction/problem: Given two charges $q_A$ and $q_B$ with values $400 nC$ and $900 nC$ respectively, and masses $m_A = 1 gr$ and $m_B = 3 gr$. charge A is gieven a velocity of $v$, and given that ...
David's user avatar
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-2 votes
0 answers
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force on circular loop due to current in long wire [closed]

my first try is take element at a distance theta from R2 then write force equation and then integrate between -90 to +90 and similarly. but it is getting more complicated. anyone solve this question
Uttkarsh Saini's user avatar
0 votes
3 answers
32 views

Electric field at a point due to dielectric inserted in between a parallel plate capacitor [closed]

Here, I have a parallel plate capacitor with each plate having surface charge density $\sigma$. A dielectric of dielectric constant $K$, is inserted partially between the two plates. What would be the ...
NPC's user avatar
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1 answer
95 views

Will the electrical potential difference between the Windward and Leeward sides of a mountain range generate electrical current?

I would like to know if it is possible that the electrical potential difference between the Windward side and the Leeward side of a mountain range, due to a thunderstorm occurring on the Windward side,...
user57467's user avatar
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1 answer
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Understanding Symmetries and Invariances in Electrostatic Fields [closed]

I'm currently studying electrostatics and I'm having trouble understanding the concepts of symmetries and invariances of electrostatic fields. I understand the basic definitions of symmetry planes and ...
Boulahya Kaouthar's user avatar
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0 answers
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Deriving the Yukawa potential from the field of a screened charge [migrated]

I am trying to derive the Yukawa potential from the electric field of a screened positive point charge, which is $$ \vec{E}(\vec{r}) = \frac{q}{4\pi\epsilon_0}\frac{e^{-kr}(kr+1)}{r^2}\hat{r}. $$ The ...
lain's user avatar
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0 votes
0 answers
29 views

Error in reasoning for electric field outside a cylinder

Suppose we have a cylinder of length $L$ with uniform charge density that has its central axis on the $z$ axis and the center of its bottom face located at the origin. Let $P_z$ be any point that lies ...
Joa's user avatar
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0 votes
3 answers
40 views

Electric dipole

I have a very silly question to ask. If two charges $+q$ and $-q$ same in magnitude form a dipole in a uniform electric field $\vec{E}$, then the force on the $+q$ charge acts in the same direction as ...
Mahito Ahito's user avatar
2 votes
0 answers
49 views

Potential of circle and $n$-gon

Consider power central fields $f \sim r^k, - \infty < k < \infty$, and unit circle, "charged" in the sense of the field. We will be interested in the potential within the circle, i.e. ...
lesobrod's user avatar
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0 answers
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Assessing Error Step Size in Continuous Charge Distributions

For obtaining the electric field for bodies at the macroscopic scale, the discontinuities in the charge distributions are ignored. A continuous function for the charge distribution is considered. But ...
User's user avatar
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0 votes
6 answers
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How will the capacitance of a capacitor reduce when the distance between the plates is increased?

Now I know that if the potential difference between the plates increase that capacitance will reduce, but for that also I thought as the distance between the plates increases, the electric field ...
Leisha Lakhotia's user avatar
1 vote
1 answer
98 views

Electrostatic potential outside of a charged ball [closed]

To preface, I have never solved Maxwell's equation or his resulting Poisson's equation in any coordinate scheme, nor am I a physics major. I'm entirely teaching myself how to do this, so I don't know ...
Researcher R's user avatar
2 votes
1 answer
63 views

Does the geometric shape of the cross-section of an infinitesimally thin conducting charged thread (wire) affect its electric field?

Assume that a solid conducting torus (toroidal ring), with a cross-section of a circle of (minor) radius $r$, is negatively charged. Solving Poisson's equation, we can find the charge distribution of ...
Mohammad Javanshiry's user avatar
0 votes
1 answer
72 views

How does this proof of Gauss’ law generalize from $1$ to $n$ charges?

I am having trouble seeing how the proof of Gauss’ law for one charge generalizes to hold for multiple charges in Griffiths’ introduction to electrodynamics. Gauss’ law is proved for one charge (for ...
Joa's user avatar
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1 answer
36 views

Will a piezoelectric material under constant pressure maintain its electrostatic charge/behave like an electret?

The question title pretty much says it all. Assuming the piezoelectric material does not decompress, I assume the electrostatic potential between its poles should remain constant. Will it maintain ...
Tindeuchen's user avatar
0 votes
4 answers
44 views

Comparing Electric Potential Energy of two Charges

I do not know what I am missing here and would appreciate a little help in figuring out the flaw in my logic. I have a row of positive charges and a row of negative charges as shown in the image above....
Zeiglar's user avatar
0 votes
2 answers
67 views

Voltage: work to move a charge, or difference of electric potential?

Let's say I have a single positive charge inside of an electrostatic field. I want to move this charge from point A to point B and determine the voltage between the two points. Points A and B are the ...
oh no's user avatar
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1 vote
3 answers
41 views

Charge besides conductor

This is a curiosity What would be net charge induced on a (say spherical) conductor when a positive charge is placed besides it. What I think is that a negative charge will be induced on surface near ...
Mainframe's user avatar
0 votes
1 answer
50 views

When Can a Set of Surfaces Be Equipotentials?

The question on the title is the name of the section 5.0.0. of Smythe's book on electromagnetism. He explains this question very briefly, but i genuinely do not understand the argument. The page in ...
QuantumBrachistochrone's user avatar
0 votes
1 answer
49 views

How can I deduce a capacitance of a capacitor without existing formulaes?

Understanding Charge Accumulation in Capacitors Connected in Series I've been exploring the behavior of capacitors connected in series and developing a conceptual model to understand how charge ...
DPV's user avatar
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1 vote
1 answer
75 views

How do conductors actually work in electrostatics? [closed]

I am mainly confused because we are learning about conductors in electrostatics, and I always think of an electric wire connected to a phone charging it (a phone charger). So, when I hear "...
dareen's user avatar
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0 votes
2 answers
49 views

Maxwell stress tensor on a capacitor late given a dielectric

Given a capacitor with large plates (area $A$) separated by a dielectric with relative permittivity $\varepsilon_r$ and thickness $g$, I believe the Maxwell stress tensor states that the force on each ...
asyndeton256's user avatar
1 vote
1 answer
61 views

I don't understand Green's derivation of the Laplace/Poisson equation inside an electrically charged body

I am currently reading George Green's "An Essay on the Application of Mathematical Analysis to the Theories of Electricity and Magnetism"Green's essay to gain some insight into the original ...
Adam's user avatar
  • 13
3 votes
2 answers
39 views

How do I compute the voltage accross a cell membrane given microstate of neuron (distribution of charged ions)?

I am not a physicist, and I'm not sure what keywords to use to search for this. I'm trying to understand how I could in theory quantitatively know, what the voltage across a cell membrane in a Neuron ...
user56834's user avatar
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1 vote
0 answers
51 views

Charge distribution in two concentric conducting shells connected by a thin wire

Above is the content of the problem in the title and I'm confused about the solution. I'm not sure whether it is correct or not. The two shells are conducting and connected, so the difference in ...
Miłosz Brzechczyn's user avatar
0 votes
3 answers
64 views

$z$-component of electric field due to a static square loop

I am having trouble finding the $z$-component of an electric field discussed in problem 2.4 of Griffith’s introduction to electrodynamics. Suppose we have a square loop of side length $a$ carrying a ...
Joa's user avatar
  • 179
0 votes
1 answer
27 views

Using an imaginary conducting shell of infinite radius to calculate capacitance of a spherical conductor

This is a statement from Serway's Modern Physics which I don't understand. It tries to explain capaticance for a single conductor. Imagine a single spherical charged conductor. The electric field ...
nomadicmathematician's user avatar
0 votes
1 answer
52 views

Self-Energy of a Conducting Shell based on Surface Charge Distribution

If a charge $q$ is given to a shell of radius $r$ (conducting or non-conducting) it's self-energy is $kq^2/2r$, $k$ being Coulomb's constant. But if the shell is conducting and the charge on the inner ...
JustAMathsGuy's user avatar
2 votes
1 answer
89 views

Confusion on the definition of dielectric permittivity

I don't understand how we're defining the dielectric permittivity, sometimes it's defined as the ability of the material to resist the electric field and sometimes as the ability to permit the ...
Manish Parmar's user avatar
-2 votes
0 answers
32 views

Is charge an intrinsic property of matter? [duplicate]

Is charge an intrinsic property of all the particles that comprise matter or is it an intrinsic property limited to certain fundamental particles only?? Or the question can be revised as "Does ...
Kunal Prajapat's user avatar
1 vote
2 answers
64 views

Why is the electric potential from a positive sphere not negative? [duplicate]

Say we have a positive point charge located somewhere. Then the electric field due to this point charge is $\vec{E} = \frac{1}{4\pi \epsilon_0}\frac{Q}{r^2}\hat{r} $ , now considering potential is $V =...
J. Doe's user avatar
  • 119
1 vote
2 answers
83 views

Densities at a Point

I was recently reading Purcell’s text on electrodynamics. He generalizes Coulomb’s Law by introducing charge densities. However, what does the density at a point represent? (Since Purcell took charge ...
V T Naveen Mugundh's user avatar
2 votes
2 answers
227 views

Dipoles as vectors

A triatomic molecule $X_2Y$ has plane structure as shown in figure. Due to difference in electronegativity, charge acquired by each X atom is $q$ and charge on Y atom is $- 2q$. The bond length ...
Anshu Gupta's user avatar
1 vote
2 answers
159 views

Does cutting out the surfaces with no surface charge affect the charge distribution on the remaining parts of a conducting surface of arbitrary shape?

Assume that we have an arbitrary conducting surface being charged positively/negatively. Also, assume that we have extracted charge distribution by solving the Poisson's equation with proper boundary ...
Mohammad Javanshiry's user avatar
1 vote
0 answers
47 views

Total charge within a sphere

Consider an electric field in free space with $$ \mathbf {D} = -3z\mathbf {a_r} μCb/m^2 $$ I need to calculate the total charge within a 3mm sphere centered at (0,1,1). I calculate the charge ...
Pavlos Papanikolaou's user avatar
1 vote
2 answers
84 views

Divergence of Electric Field of Point Charge is always zero [closed]

I might have a bug in my brain, but I just can't figure this out. Please help. According to the first of the Maxwell Equations, we have $$ \nabla\cdot\vec{E}=\frac{\rho}{\epsilon_0}. $$ And we have ...
tobi-v's user avatar
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0 votes
0 answers
35 views

Question about electric field around charge density

Suppose the region $0 < x < d$ has charge density $-p$, and the region $-d < x < 0$ has charge density $p$. Why is electric field on the edge of region in point d zero? If negatively ...
Kopun Vukašin's user avatar
0 votes
2 answers
68 views

Is charge an intrinsic property of "all" the fundamental particles or an intrinsic property of "certain" fundamental particles?

Charge is said to be an intrinsic property of particles of which matter is made of. First of all, what does the word "Intrinsic" actually signify in this context?? Does it mean that "...
Kunal Prajapat's user avatar
2 votes
2 answers
109 views

Confusion with treatment of unit vectors in electrostatics

I am reading Griffiths’ Introduction to Electodynamics and there are two problems where the methodology for treating unit vectors in integrals seems inconsistent to me. When we are trying to find the ...
Joa's user avatar
  • 179
0 votes
0 answers
36 views

Both charge and mass are intrinsic properties of matter. So for the existence of matter, should both mass and charge exist simultaneously? [duplicate]

Recently, I came across a book which stated that "Mass can exist without charge but Charge cannot exist without mass". Is this statement really correct? As if we look intrinsically in a ...
Kunal Prajapat's user avatar
1 vote
1 answer
23 views

Electric field at any point in the region between two capacitors is proportional to the magnitude of charge on each conductor

This is a statement from Young and Freedman's University Physics Section 24.1 on Capacitors. Suppose we have any two conductors with charges $-Q$ and $+Q$ on each charged with a battery. Then this ...
nomadicmathematician's user avatar
11 votes
2 answers
513 views

Why is nonzero net charge density incompatible with the cosmological principle?

In an answer to a question about the overall charge-neutrality of the universe, benrg writes, A nonzero net charge density is incompatible with the cosmological principle. Unlike the gravitational ...
rob's user avatar
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5 votes
3 answers
414 views

Why is the universe charge-neutral?

The positive charges (such as from the protons) of the universe are almost neutralized by the negative charges (such as from the electrons). Is there an explanation for this neutrality? Does it ...
MadMax's user avatar
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2 votes
1 answer
40 views

Bound Charges in Polarized Material

I'm currently working my way through chapter 4 of Griffith's Introduction to Electrodynamics (4th ed) and I ran into an issue with his notation. In chapter 4 sectin two, when calculating the electric ...
ReggiePlasmaQs's user avatar

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