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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Vector question, differentials, Electromagnetism

I was reading this demonstration of electric potential in my book: Let $q$ be a point charge at point $P$ The Electric field created at point $M$ by $q$ is : $$\vec{E}(M) = ...
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1answer
33 views

How should I interpret the math in showing that the potential difference and the emf in an ideal battery are the same?

I was reading Griffiths' Introduction to Electrodyamics where he says that in order to have the same current through out a circuit there are two force per unit charges acting on the circuit, $f=f_s+E$ ...
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0answers
32 views

Electric field of two charges in point (0,0) [on hold]

I have a question about calculating electric field. In the given image you have two line charges which are not infinite. “a” is a radius, and angle “alfa” is given. How to calcululate electric field ...
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1answer
14 views

How is the electric potential of a localized charge distribution scaled when scaling the geometry of the problem?

I am trying to find the potential at a point on the surface of a charged polygon (rectangular). I have find a solution to the problem, but it relies on the following statement: If the potential at ...
0
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1answer
60 views

Gauss's law not making sense

If we have a point charge and outside of it we have a non-conducting Gaussian sphere, then Gauss's law says that the net flux should be zero. I agree that the total field lines coming in are equal to ...
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1answer
9 views

Repulsive force between same charged plates?

I understand that the attraction force between parallel plates of capacitor is the derivative of stored energy with respect to distance of the plates. But how could we find the repulsive force between ...
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0answers
26 views

Electricity, Gauss's Law and Electric potential [on hold]

could you please help me to start? I know that I need to use Gauss's Law and Electric potential to solve this problem but I have no idea how to set this up.
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2answers
42 views

Potentials with no sources

I have been reading Electrostatics from Panofsky's book. One of the exercises in his first chapter is Functions of the type $\phi = x$, or indeed $\phi = x^2 + 2 y^2 - 3z^2$ , satisfy Laplace's ...
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1answer
44 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 ...
5
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2answers
58 views

Poisson equation in 2D and 3D: geometrical reason for the difference

The Poisson equation in 3D shows a fundamental solution in 3D which decays with $\sim 1/r$, whilst in 2D it shows a much different decay $\sim -\ln r$. While in 3D not only the solution, but also its ...
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0answers
15 views

What are the risks of touching a positively charged lead to a negatively charged lead? [on hold]

this is my first time asking a question here so hopefully I frame it correctly. I have two electrodes that are charged to opposing positive/negative potentials. I need to place them in fairly close ...
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0answers
18 views

I need help with this question requiring the distance of null electric field [on hold]

The question goes: Two charges q1=-10^-5 C and q2=-9x10^-5 C are placed respectively at two points A and B, 40 cm apart. The electric field is null at point C. Find AC I have tried getting the force ...
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0answers
17 views

I need help with this question on electric fields [on hold]

Two charges q1=-10^-5 C and q2=-9x10^-5 C are placed at two points A and B, 40 cm apart. The electric field is null at point C. Find AC
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0answers
28 views

Laplace equation between circles [on hold]

I need to solve the simple Laplace equation $$\nabla^2f(r,\theta)=0$$ with boundary conditions: $$f(a,0)=g(\theta)$$ $$\lim_{A\rightarrow\infty}f(A,\theta)=1$$ what would be a straightforward way to ...
2
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1answer
42 views

Gauss's Law of Electric Field how it actually works? & How Gauss derived it?

I want to know how Gauss derived his equation of Electric Field. Did he derive it from Coulomb's law? I don't think so. Please tell me some details about how this law works? inside a Gaussian ...
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1answer
32 views

What exactly is electric dipole moment & how it works?? and Why Electric Dipole Moment vector's direction is from negative charge to positive charge?

What exactly is electric dipole moment & how it works/used? (don't go into deep mathematical calculations) Please answer the question about the direction with good details. Don't just say that ...
6
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2answers
459 views

Why is Xenon favored as the propellant in electric thrusters?

Most of the articles I've read on electric thrusters mention that Xenon is generally, with some exceptions, used as the propellant (or would it be termed reaction mass?). They never mention why ...
0
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0answers
21 views

D'alembert's principle and its implications in the case of Electric and Magnetic fields [on hold]

I am having few confusions about EM fields especially questions about the consistency of the postulates of EM theory in case of electrostatic interactions and I did try to view it through the window ...
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1answer
20 views

Potential of 2 parallel plates

How can I write down a potential of 2 parallel plates (area $A$) with charge $+Q$, $-Q$ such that V(inf)=0 and V(in) is what I would expect, $Ed = Qd/A\epsilon_0$. Do I have to write a discontinuous ...
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1answer
21 views

Does wearing jewelry increase chance of static electricity

I am the only one in my office repeatedly subject to static stock. Does wearing silver jewelry increase my chance of getting a shock?
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1answer
24 views

2D room with electron-point-charges (stability)

Is there a fast way to find out stable #"point charges" & constellation for this kind of Simulation. The 2D repeating itselve in each direction till infinity, so i've a kind of symetrie here. ...
2
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3answers
404 views

How much energy is needed to create an electron?

I know how to calculate the electrostatic energy of a sphere (it has a well defined radius). But how can I calculate the electrostatic energy of an electron as it is a point particle? By electrostatic ...
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0answers
22 views

Interaction between charged particles through static electric fields [duplicate]

I generally find it pretty primitive to accept that static charges communicate with the help of static electric fields without any exchange going on between them such as electromagnetic waves. I ...
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0answers
16 views

Did Insulators are antistatic materials? [closed]

I like to know the all the insulating materials are antistatic materials.
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2answers
62 views

How to get the electric field strength of a plate as approximation of a sphere

Suppose you know that the electric field in distance $r > R$ from the center of a charged sphere with charge $Q$ and radius $R$ is given by: $$ E = \frac{1}{4\pi\epsilon_0} \frac{Q}{r^2} $$ ...
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1answer
37 views

Force between two point dipoles

What would the force between two parallel point dipoles be? I was thinking of doing it the way force between two point charges is found out, by finding the field and then the force but I am not able ...
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1answer
43 views

Can an electric field align water molecules?

Water is a polar molecule, which means it has an uneven charge distribution. How much of an electric field strength would it take to align all, or most, of the molecules at room temperature?
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1answer
60 views

Proof that the electric field is conservative

I was told a proof that the electric field was conservative (without using $\nabla$) which used a point charge and showed the following: $$w.d.=\int_c{\vec F \bullet d \vec l}=\int_c{\vec ...
3
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1answer
145 views

Need of small charge in definition of electric field?

Why do we need infinitesimally small charge in definition of electric field? Since the test charge cannot exert force on itself, F on test charge will not change whatever the value of test charge q ...
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0answers
10 views

Nylon vs PVC triboelectric series

If we charge a nylon rod and a PVC rod using friction, and discharge them individually to a metallic object to measure how much charge they can tranfer, it can be seen that the charge taken out by the ...
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0answers
59 views

Magnitude of Electrical Forces Between two objects?

Two identical 500-mg paper clips, 1 and 2, dangle from two strings, the top ends of which are tied to the same nail. The clips are charged in such a way that the two strings hang with an angle of ...
0
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2answers
33 views

Electric potential inside shell

Suppose we have a hollow neutral shell and $q$ charge at $r$ from its center now we take a point a someplace other than center then will electric potential change? I don't think because electric ...
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1answer
87 views

Green function solutions in electrostatics

I have a conducting plate on $x$-$y$ plane. So I have a boundary condition at $z=0$ $\Phi=0$ but, for $z>0$ I have a point charge at z=a which is expected to create a potential. $$ ...
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3answers
53 views

How can we assume that we're in electrostatics if we are talking about current?

In the textbook I am currently reading it states that to even out the flow of current throughout a circuit, the force required is of the form $f=f_s+E$ where $f_s$ is from the battery or other energy ...
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5answers
118 views

Physical interpretation of the statement $\oint E\cdot dl=0$

Can anyone provide me with a physical interpretation of $\oint E\cdot d\ell=0$ in electrostatics?
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0answers
21 views

How to prove that the electric field strength in the interlayer is radial?

This is a structure modified from a typical metal spherical capacitor: half of the interlayer is now filled with one kind of uniform, isotropic, and linear dielectric medium whose dielectric constant ...
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1answer
58 views

Charge inside a shell

There's a positive charge Q inside a neutral conducting shell. An external field is applied. I learned that there can be no effect in cavity due to external things (electrostatic shielding), so ...
2
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2answers
56 views

Is there such thing as an evenly-charged sphere?

Let's begin with a very typical model seen in almost every electromagnetics textbook: a solid, evenly-charged sphere. First it cannot be a conducting sphere because charge will automatically ...
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3answers
458 views

Why is surface charge distribution uniform for a conducting sphere? Can't it be arbitrary?

If the charge $q_1$ has to repel the charge $q_2$, the electric field has to go inside the conductor which contradicts the fact that electric field inside conductors is zero. Then why do the charges ...
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1answer
42 views

Electrostatics problem concerning induction by a point charge inside a conducting shell

Consider two independent conducting shells (not thin shells! i.e., their internal and external surfaces do not overlap.) whose shapes of external surfaces are identical but internal surfaces are not ...
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1answer
26 views

Preventing Electricity Leakage With Insulators

If we charge an object made of insulating material, the charges on it would leak to the medium as the time passes, due to the potential difference. I would like to know if there is a way to prevent ...
0
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0answers
34 views

Electrostatic ion thruster neutralizers

All electrostatic Ion thrusters have a neutralizer electron beam, but why are they required? Is avoiding the accumulation of negative charge the only reason? I would've thought that the main reason ...
2
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0answers
19 views

Approximating electrostatic grids as a multipole expansion

Is there a known good summary, or a succinct algorithm to compute the far-field approximations of an arbitrary set of electrostatic surfaces set at different potentials? I'm looking to model a ...
0
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1answer
26 views

Any economical quantitative electrostatics experiments for the university level?

I'm seeking for some safe experiments for undergraduates in the electrostatics context. We have a Van-de-Graaff generator in our fundamental physics lab but this kind of devices are useful for ...
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1answer
71 views

Is it equivalent to derive Gauss's law from discrete and continuous source distributions?

I've seen two derivations for Gauss's law in electrostatics. The first assumes a discrete charge distribution, the second a continuous one: Use superposition $$\vec{E}=\sum_{i=1}^n\vec{E}_i,$$ so ...
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1answer
57 views

Why is static electricity called static?

They called it "static" because it doesn’t go anywhere. To create static electricity, you have to rub two different materials. At the moment you rub them, the electrons already moved. So how come ...
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1answer
55 views

The advantages of a dielectric in a capacitor

In a capacitor a dielectric can be placed in between the two plates. I have trouble understanding the points / advantages of a dielectric from what I have read in a text book. The points written there ...
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1answer
40 views

A query regarding constant $\frac{1}{4\pi \epsilon_{0}}$ in Coulomb's Law [duplicate]

In our physics class we were discussing about Coulomb's Law and equation for the electrostatic force between two points: $$F_{e}=\frac{Q_{1}Q_{2}}{4\pi \epsilon_0 r^2}$$ From the equation a query ...
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1answer
27 views

Electric Field Contributions

Figure 1: Two thin parallel wires Figure 2: The cross section of a hollow sphere containing a smaller, hollow sphere The electric fields for both figures are calculated using different principles. ...
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1answer
56 views

Electrostatics of Conductor

In an isolated conductor the extra positive or negative charges will be distributed on the surface uniformly. Hence there will be no charge inside the conductor, hence no field. But what accounts for ...