Electrostatics is concerned with the field and potential of stationary electrical charges and electric charge distributions. Problems are this type are almost exclusively concerned with mathematics of geometries using the inverse-square law.

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How to calculate electric force between two tubes?

Let's say the electric field due to a charged tube is $E$,length of the charged tube is $l$, radius is $r$ and the surface charge density is $\lambda$. I know that to calculate the electric force ...
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Spherical charge distribution along a wire of length $L$ in which its center coincides with the origin of the system

I've already tried to find the expression but I don't find the expected result for the quantity of charge when I use the expression I found. For example, I checked it by integrating the expression ...
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1answer
31 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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14 views

How to calculate the electrostatic force between two dielectric rings of charge?

Let's say there is a dielectric ring of charge with radius $a$ and charge $q_1$. I could calculate the electrostatic force applied on a point charge with charge $q_2$ and which is collinear with the ...
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1answer
14 views

Can non-conductive materials can be grounded by a wire?

Suppose that I comb my hair. The plastic comb would become negatively charged and would attract small paper pieces. But if I touch the comb in bare hand and in bare foot standing on the ground, or if ...
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39 views

Some general questions about static electricity ( ex : Combing the hair ) [on hold]

We know , static electricity is built up when i comb my dry hair. what type of charge is gathered in comb & what type of charge in hair ? ( i.e. + or - charge ) why would charges would gather ...
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6 views

How to calculate the electrostatic force applied on an object that is along the axis of a charged tube's surface?

Let's say there is a charged tube(a cylinder with no top and bottom) with radius r and length l, charge q1 which also made out of insulating material. And also if there is an object with charge q2 ...
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28 views

How to calculate the electrostatic force applied on an object that is along the axis of a charged tube?

Let's say there is a charged tube(a cylinder with no top and bottom) with radius r and length l, charge q1 which also made out of insulating material. And also if there is an object with charge q2 ...
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29 views

Circuit breaker Trips during thunderstorm

The circuit breaker at the electrical mains trips at home when there is a thunderstorm outside. Why does this occur?
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1answer
19 views

Conducting sphere with a cavity

I have a conducting sphere which has a cavity in it. The cavity is not at the center of the sphere. If a charge $+q$ is placed inside the cavity (with the sphere remaining neutral as a whole), what ...
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1answer
28 views

Two spherical cavities hollowed out from the interior of a conducting sphere. At the center of each cavity a point charge is placed

From Griffiths: Two spherical cavities, of radii a and b, are hollowed out from the interior of a (neutral) conducting sphere of radius R. At the center of each cavity a point charge is placed – ...
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34 views

Physical interpretation related to a non-linear partial differential equation

I am doctoral student in pure mathematics working on a particular problem. My question is if this problem has applications to real world phenomena. I will try to explain the direct problem starting ...
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0answers
32 views

How to calculate the electric field for a charged tube? [closed]

Let's imagine there is a non-conducting charged tube with uniform charge distribution. (Simply a cylinder with no top, bottom and inside. I mean a roll of 2 dimensional paper but there is no inside. I ...
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1answer
41 views

What would happen if charged plates are placed horizontally?

My idea is placing charged conducting plates in such a way that they won't see each others' surfaces unlikely to the typical design of parallel plates. If they are placed like this, would be the force ...
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2answers
99 views

What does really attracts a water stream to a charged object?

I saw this video by Varitasium and I was not 100% sure about the third phenomena, a statically charged object attracting a stream of water, especially because he explicitly mentioned that it is not ...
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0answers
28 views

What do we mean by electromagnetic charge? [duplicate]

What do you mean by charge? Why should a particle have a charge?
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1answer
45 views

How can I apply to the differential form of Gauss' Law? [closed]

I'm trying to learn Maxwell's equations but I got stuck. I couldn't understand the usage of the differential form of the Gauss' law. How can it be applied to questions? For example, let's say there is ...
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1answer
48 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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1answer
43 views

Why is electric potential positive?

If there is a positive charge $q$ at the origin of a coordinate system, the electric potential $\phi$ at a distance $r$ from $q$ is (by definition, if we take the point of zero potential at infinity): ...
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1answer
44 views

Does charge distribute itself uniformly on a conductor?

An excerpt from a beginning E&M book [...] In other words, the surface of a conductor is an equipotential surface under static conditions. [...] Summarizing the boundary conditions at the ...
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19 views

name for 2D Electrostatics as Integrable System

I am trying to understand 2D electrostatics of $n$ point charges. Roughly, $$ H = \sum_{i=1}^N n_i \ln |z- z_i|$$ However, I keep bumping across the Gaudin model instead with this Hamiltonian $$ ...
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1answer
26 views

Potential energy of a dipole in a uniform electric field convention?

When finding the potential energy of a dipole in a uniform electric field, I was told by my lecturer that the convention is that the potential energy is 0 when the dipole moment and electric field ...
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2answers
131 views

What restores balance to a repulsive electric force on an electroscope?

I am an amateur physics enthusiast (during the day I am a police officer), and recently, I learned how to build an electroscope. I regret that I am learning how wonderful our universe is so late in my ...
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1answer
60 views

Electric field strength at the center of an equilateral triangle

Questions: Three $x$ m long rods form an equilateral triangle. Two of the rods are charged to $+q$ C and the third to $-q$ C. What is the electric field strength at the center of an equilateral ...
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84 views

Fluctuation interaction between two uncharged spheres

I'm trying to figure out quantitatively what is the force, acting between two uncharged conducting spheres and I've got stuck. It is not a kind of homework - it is just a simple act of curiosity. I'd ...
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0answers
28 views

Earthing of conductors [closed]

Can anyone please explain me the process of earthing of a spherical conductor in detail. I am aware about the basic idea of earthing but I am not able to understand and visualize it properly.
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2answers
41 views

Can I calculate the current of any setup with capacitance by the same formulae?

There are known formulae relating a capacitor's voltage and current in its classic form (battery, wires, a capacitor circuit), but what if we had a charged plate (-ve), then we put on one of its ...
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49 views

Sign error in calculating the electric field of point charge

I have to determine the electric field of a point charge, I get a true result except for a sign. Here is my passages. $$\nabla \cdot e = \frac{\rho}{\epsilon}$$ $$e = - \nabla u$$ $$\nabla^2 u = - ...
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1answer
38 views

Flaw in the radius of a spherical electron model (classical electron radius)

My textbook asks me to derive an equation for the potential energy ($U$) of sphere ($r_0$) filled with an electric charge of uniform density ($\rho$), expressed in terms of the total charge $Q$. The ...
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3answers
110 views

Variation - Electric pressure on a sphere?

I solved the following question(Answer is correct): Find the force with which two hemisperical parts of a uniformly charged hollow sphere repel each other?(charge density: +$\sigma$) Answer: ...
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0answers
32 views

Why does proton and electron attract each other? [duplicate]

Not that their charges are opposite! "+" & "-" are the signs we named them. By nature Why do they attract each other? And Why do they repel each other?
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1answer
60 views

Why do we consider the electric field of an infinite plane? [closed]

I never understood why one would calculate the electric field surrounding an infinite plane, if such thing does not exist. Is there physical motivation for using this model? Are the results applicable ...
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1answer
56 views

From where does the sound come from when two charged objects meet in real life?

I am sure all of us have played with rubbing things and producing static electricity and when I was charging my comb by rubbing it on my hair and watching it attracting a small piece of paper, I heard ...
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3answers
96 views

When to use method of images in Electrostatics?

I am a bit confused about when to use the method of images in E&M? For example, in Griffith's Electrodynamics Example 3.2, the problem reads: A point charge $q$ is situated a distance $a$ from ...
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2answers
65 views

Positive charges “move” from higher to lower potential [closed]

It's my understanding that whenever an object gains or loses electric charge this actually corresponds to losing/gaining electrons (protons do not move). So how can a positive charge always move from ...
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1answer
76 views

Minimum separation problem

I am trying to solve this problem where two point charges are infinite distance apart(horizontally) but separated by some finite distance vertically. Both are positively charged and projected ...
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0answers
24 views

Electrochemical cell potential - Prigogine book

I'm trying to understand equation 10.2.14 from Prigogine book "Moder thermodynamics": $V=\frac{\tilde{A}}{nF}=\frac{1}{nF}\left(\mu_X^R+\mu_Y^L-\mu_{Xred}^R-\mu_{Yox}^L\right) - \left( \phi^R-\phi^L ...
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0answers
29 views

Polarizable molecule in E-field

If we have a linear molecule with a dipole moment $\mu$ in a static electric field $E$, the potential is given by $V = - \langle \mu,E \rangle$. What is the appropriate equation for the potential if ...
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3answers
153 views

How to solve the Laplace Equation in the hollow square region?

Suppose the values of $a$, $b$, $V_1$ and $V_2$ is given. I want to find the solution of the Laplace equation, $$\frac{\partial^2 \phi}{\partial x^2}+\frac{\partial^2 \phi}{\partial y^2}=0$$ in the ...
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2answers
30 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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6answers
589 views

What is the range of the validity of Coulomb's law?

What is the smallest and biggest distance in which Coulomb's law is valid? Please provide a reference to a scientific journal or book. Just saying that this law is valid from this range to that range ...
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0answers
15 views

Is there a simulator for observing the force between two charges comprehensively? [duplicate]

I basically want to observe the electrostatic force between two charges. I want to know if is there a simulator which could both help me to observe and calculate the force between two charges. I ...
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0answers
20 views

Is there a simulator for observing the force between two charges?

I basically want to observe the electrostatic force between two charges. I want to know if is there a simulator which could both help me to observe and calculate the force between two charges. I ...
4
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4answers
314 views

Divergence of a field and its interpretation

The divergence of an electric field due to a point charge (according to Coulomb's law) is zero. In literature the divergence of a field indicates presence/absence of a sink/source for the field. ...
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1answer
52 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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0answers
28 views

Electrostatics with Yukawa mass

I seem to have forgotten how to solve Laplace's equation when there is a Yukawa mass $\mu$. I want to find the Yukawa potential due to a homogeneously charged sphere of radius $R$ and charge density ...
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0answers
16 views

Surface potential resulting from the charge transfer between insulator and conductor

Common non-contact electrostatic voltmeters are used to measure the surface potential. Imagine we place a charged insulator on top of the conducting plate (insulated from the surrounding) and measure ...
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2answers
31 views

Electrostatics - Inserting a brass plate between two charges

The question is: if I were to insert a brass plate between two charges, what will happen to the force between the charges? Would it increase, decrease or stay the same? Does the brass plate increase ...
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1answer
44 views

Maxwell calculations that predicted the generation of waves (further use for wireless telegraphs)

At this point in this documentary about the history of electricity: https://www.youtube.com/watch?v=oPnS2WO2_0k&t=4m40s the guy says the Maxwell calculations predicted the generation of certain ...
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1answer
57 views

What gives an elementary particle a charge? [duplicate]

We know that proton is positive, and electron is negative. But where does come notion of negativity and positivity? Does charge come from some specific particles, or they specific order?