# 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.

7,935 questions
Filter by
Sorted by
Tagged with
1 vote
25 views

### 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 ...
1 vote
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 ...
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 ...
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 ,...
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 ...
• 4,912
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 ...
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 ...
16 views

### 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
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 ...
• 21
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,...
• 478
33 views

### 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 ...
19 views

### 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 ...
• 1
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 ...
• 179
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 ...
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. ...
• 163
42 views

### 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 ...
• 1
117 views

### 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 ...
1 vote
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 ...
• 121
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 ...
• 2,503
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 ...
• 179
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 ...
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....
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 ...
1 vote
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 ...
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 ...
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 ...
• 13
1 vote
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 "...
• 31
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 ...
1 vote
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 ...
• 13
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 ...
• 1,772
1 vote
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 ...
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 ...
• 179
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 ...
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 ...
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 ...
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 ...
1 vote
64 views

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 ...
• 91.5k