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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Charging a spherical capacitance

How could one charge a spherical capacitor with a battery or any other emf source?
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0answers
31 views

Effect of humidity on static electricity

I am looking for a reference to a scientific paper or textbook that explains the effect of humidity on static electricity (triboelectric effect). Any help will be highly appreciated.
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0answers
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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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1answer
118 views

An Electric Potential Glued to a Cubic Insulator to Replicate a Point Charge: Charge Distribution

I have been going back over this problem with a friend for the better part of a day: A potential is glued to a cube insulator so that outside of the insulator the field is the same as a point ...
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2answers
30 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
117 views

How does food plastic wrap get positive and negative charges on opposite sides of the plastic?

Related: Why two objects get charged by rubbing? After reading the above question’s answer given by Luboš Motl in terms of the triboelectric effect, I believe I have a good grasp on how charge is ...
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1answer
47 views

Earnshaw Theorem for ionic solids

Is a single molecule of sodium chloride (say) or a cluster of molecules of NaCl unstable, although macroscopically NaCl is in fact, stable? How can I reason this based on Earnshaw's theorem?
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1answer
42 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
38 views

What is the potential field of an ion near the Bohr radius?

I figure that at large enough distances, the potential field of an ion is just the Coulomb potential for its net charge. But what happens at scales comparable to the ion's Bohr radius? Could there be, ...
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1answer
55 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?
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3answers
37 views

Insulators (also called Dielectrics) which cannot conduct Electricity

How Dielectrics as an Insulating materials transmit electric effect without Conducting Electricity ? How its Possible ??
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2answers
24 views

Principle of superposition for capacitor

In a capacitor the parallel plates of opposite charge create equal electric fields in opposite directions. We know field outside the capacitor is zero but inside the capacitor it is non zero. My ...
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1answer
162 views

How can one explain the Kelvin Water drop experiment without assuming the container to already possess a positive charge?

Kelvin Water Dropper experiment refers to the electrostatic generator invented by Lord Kelvin, which uses falling water to generate a voltage by electrostatic induction occurring between ...
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2answers
41 views

Grounded conductor inside a uniform electric field

I am working on a textbook problem of a grounded conductor inside a uniform electric field. The textbook states that "grounded" means potential = 0. In my opinion, "grounded" should mean "same ...
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0answers
31 views

Dipole charge attractions while one of them is turning around other [closed]

There is a electric dipole which is fixed. So angular momentum isn't conserved. And there is charge $Q$ which has initial velocity $u$. My question is: What is the tangential velocity of the charge ...
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0answers
32 views

Why a transistor is activated when I touch its base with my finger? [closed]

Is my body charged eletrically? If so, how much? Will it work with all types of transistors?
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1answer
155 views

Concept of separation of charges in lightning clouds

I have read in an article that when lightning strikes in the clouds the cloud disintegrates into two parts of which the negatively charged part is bigger than the positively charged one. Why does this ...
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1answer
100 views

Charging a Capacitor?

How is the charge +q given to the one plate to the capacitor with the help of a battery,does the battery remove electrons from the plate and +ve charge gets accumulated on one plate?Does it? And one ...
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2answers
140 views

Electric field in a sphere with a cylindrical hole drilled through it

Suppose that you have a sphere of radius $R$ and uniform charge density $\rho$; a cylindrical hole with radius $a$ ($a\ll R$) is drilled through the center of the sphere, leaving it like a "necklace ...
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5answers
520 views

Why is the electric field of an infinite insulated plane of charge perpendicular to the plane?

I'm studying Gauss' Law, and I came across a section where we're supposed to find the electric field of various shapes (like an infinite line of charges, etc), and for an infinite plane with a uniform ...
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1answer
29 views

How is the charge concentrated at the centre of shell for calculating potential from it?

While calculating electric potential due to a spherical shell at a point outside the shell, why do we say that the entire charge is present at the centre of shell? Is this true even if the charge on ...
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2answers
56 views

Electric field represented by parallel curves

In a region of space, I have an electric field represented by parallel curves as shown in the diagram. The curves are equally spaced. We know that a uniform electric field can be represented by ...
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4answers
181 views

Temperature and resistance?

Why does resistivity increase with temperature? The explanations I have heard so far are that increasing temperature increases vibrations in the lattice structure resulting in the number of ...
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1answer
31 views

Protect drone from lightning [closed]

I am designing a dirigible, robotic drone. It is basically a polyurethane airship, approx 3.6 m length and 2.1 m diameter. I am worried about lightnings: as far as I know, a Faraday Cage should be ...
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2answers
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Why does charge distribute evenly between two halves of a conducting sphere?

Always while studying I was told that if two identical spheres, one charged and the other uncharged, are brought together the charge in each one of them is halved. However, why does it happen? Is it ...
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2answers
67 views

Divergence of conservative electric field

I have a little doubt about the following: according Gauss law in the form of Maxwell's equation, we know that: $$ {\rm div} (D)~=~ \rho(v) $$ This just tells us that the electric field has nonzero ...
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3answers
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Is the electrostatic field inside of any closed, uniformly charged surface zero?

We know that a simple application of Gauss's law tells us that the field inside of a uniformly charged spherical shell is zero. Does this hold for all uniformly charged closed surfaces? If so, how ...
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2answers
60 views

Electric Potential of a sphere given electric field

I'm studying for a course in electromagnetism, and I've been given an electric field for which I need to find the associated scalar potential. The field is the field generated by a sphere of radius ...
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0answers
23 views

Variation of Electrostatic Potential with Distance in a Uniform Field

I came across this question in a problem book: If a proton is released from rest in a uniform electric field, does the electric potential at those points where the electron moves increase or decrease. ...
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1answer
103 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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1answer
20 views

Help in Basics for Capacitance

How does capacitor store a charge? I'm a little bit confused, as I know that a capacitor stores charge but how does it do so?
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2answers
139 views

Question on conduction

I already know that a charged polyethylene plastic (done by rubbing it with paper) can be used to attract a cardboard. Now, can I 'charge' the cardboard by touching it with the plastic? Supposedly, ...
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0answers
23 views

What causes charge buildup in a cloud before a lightning storm?

I am curious what causes the charge build up in a cloud before lightning occurs. I have seen in a few places such as this, that the process is not fully understood. Is this some form of static ...
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1answer
41 views

Could you make a Faraday cage with a different force law?

Gauss' law depends on the mathematical form of the Coulomb force. However, the phenomena that static charge resides on the surface of a conductor, and that you can't have electric fields within a ...
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1answer
76 views

How do I place point charges when using the method of images with a sphere?

We have a point charge $q>0$ in vacuum at a distance $a$ from the center $M$ of an isolated metal sphere that has a total charge $-q$ and radius $R$. ($a>R$) A) Use the method of images ...
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3answers
384 views

Question regarding inverse relation of resistance with area of cross section

It is said that resistance is inversely proportional to area of cross section. But greater area will have greater electric flux, and greater electric flux will have greater magnetic flux, and greater ...
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1answer
37 views

Potential in the middle of a square [closed]

Find the electric potential in the middle of a square with side length $a$ and charge $Q$. If I put the origin in the middle of the square, for the potential I get: ...
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3answers
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Conductors connected with a wire

Let's say I have two spherical conductors with different radii and different amount of positive charge on them. The spheres are far enough from each other. I connect them with a conducting wire. I'm ...
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2answers
44 views

Charge inside a sphere

Suppose I have a sphere of radius $r$ with all the charge residing on the surface, distributed uniformly i.e. charge density $\sigma$ is constant. I want to find the electric field created by this ...
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1answer
93 views

Total number of electric field lines coming out of a proton?

I have to calculate the total number of electric field lines through a proton. I tried using Gauss' Law, i.e, $$\phi = \oint\boldsymbol E.d\boldsymbol s = {\frac{q}{\epsilon_0}} $$ $$So, \phi = ...
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6answers
662 views

Is there a momentum for charge?

Since mass and charge behave similarly, so, just like center of mass, I define a point center of charge, that is defined by $$\vec r_{qm} = \frac {\sum{q_i \vec r_i}} {\sum{q_i}}$$ where $\vec r_i$ ...
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2answers
50 views

Basic of Capacitor

I've 2 capacitors; plate area, difference between plates and dielectric is same. Only thing is that the metal used in plates is different. Since the formula $\displaystyle C=\frac{\varepsilon A}{d}$ ...
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3answers
53 views

Limitation of Gauss's Law

We can use Gauss's law to find out the electric field $\vec{E}(\vec{r})$ due to an infinite cylinder of charge. But if the cylinder is of finite length then it is said that $|\vec{E}(\vec{r})|$ is ...
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1answer
21 views

Why defects moderate (reduce) electric field?

I am running a simulation with drift-diffusion equation, Poisson equation and Fourier heat equation with a metal/insulator/metal structure. In my simulation, initially electric field is at the top of ...
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1answer
65 views

What would be physics of a star totally consisting of electrons? [duplicate]

What is the minimum radius and mass (if any) for such a structure to be stable? What is the ultimate future of such structure? Will the electron repellation always be stronger than any gravitational ...
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2answers
59 views

Gauss's Law for a Uniformly Charged Solid Sphere [duplicate]

We want to calculate $\vec{E}$ at a distance $r$ from the center $O$ of a spherical polar coordinate system. Let the point on the Gaussian surface at which we want to calculate $\vec{E}$ is ...
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1answer
423 views

Solving by using Gauss law [closed]

Task: find the vector $ \mathbf E $ in the center of the sphere with radius $R$, which has charge volume distribution $\rho$ , $$\rho = \mathbf a \cdot \mathbf r ,\qquad \mathbf a = ...
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1answer
76 views

Which symmetry for which distance function

For evaluating the electric field of some charge distribution one can use $$\phi(r):= \frac{1}{4 \pi \varepsilon_0}\int_{\mathbb{R}^3} \frac{\rho(r')}{||r-r'||_2} dr'.$$ My question is: What symmetry ...
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1answer
46 views

Inconsistent integral and distance in spherical coordinates

I am currently studying this problem: 14 b) There you see an integral $$A(r) = \int f(\theta) (-\sin(\phi), \cos(\phi),0) d \Omega$$ where $f$ is the function containing all the rest of the integrand ...
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0answers
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Electric Potential due to conducting sphere and conducting shell

The problem statement, all variables and given/known data A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow spherical shell. Let the potential ...