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 [tag:electromagnetism] and/or ...

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Potential energy of a shell & point system

Consider the system of a point particle with charge $q$ and a spherical shell with uniform charge $Q$ and radius $R$ whose center is a distance $r > R$ away from the point particle. I'm trying to ...
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2answers
38 views

Electric field at surface of a spherical shell

The shell theorem provides a well known result that for a spherical shell with uniformly distributed charge $Q$ and radius $R$, the electric field at a distance of $r$ from the center is: ...
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2answers
12k views

Electric field of a negative charge

How was it discovered that the electric field of a negative charge points towards the charge itself? Is it true? (Courtesy of wikipedia)
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2answers
39 views

Relationship between work and energy in an electrostatic system

I am having problems understanding the relationship between the concepts of Work and Energy in a electrostatic system. As I know, the definition of Potential Energy is the ability to do work. In a ...
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2answers
137 views

Question regarding Van De Graff generator Belt

I have made a VDG generator with a rubber band as the belt and a glass roller. It doesnt seem to work because I think the rubber band may be conductive. I was thinking of using other materials for ...
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2answers
178 views

Electric Potential Energy

When work is done on a positive test charge by an external force to move it from one location to another, does the potential energy increases or decreases, and does the electric potential increases or ...
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2answers
47 views

If Electric field is constant in a region, does it imply potential is also constant?

I am a bit confused about these concepts- when is electric field or electric potential constant so i would appreciate if anyone could brief me about these things as well. Here i am referring to ...
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Gauss law vs Coulomb law similarity [duplicate]

In Feynman lecture it is stated that Gauss law will valid until inverse square law of electrostatic force (Coulomb law) otherwise it is not. How its possible?
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1answer
42 views

Gauss's law, electrical flux density [closed]

Q. Given a 60-μC point charge located at origin, find the total electrical flux passing through the plane z = 26 cm. I can understand what the question means, but I can't do anything. Is it using ...
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66 views

Mutual $E$ force due to charged coaxial rings [closed]

I found the following question in a good physics book I was solving and although this is a computer problem, I wonder if it can be done without using computers. $Q.$ Find the force of attraction ...
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2answers
23 views

Is Emf induced in the coil when magnetic Flux passing through it is zero? If so then what is the explanation?

I thought Emf would not be induced if the coil doesn't cut the magnetic Flux . But since the graph in my paper shows Emf is induced when magnetic Flux is zero , I got confused. I thought since the ...
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7answers
976 views

Why do two ends of a long conducting wire have the same electric potential?

I am not seeing the "big picture" here. If I have two conducting spheres separated by a long conducting wire, why would the spheres share the same electric potential? I think of the spheres as point ...
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2answers
194 views

Two charged spheres connected with a conductor

I have a problem with a electrostatics problem: there are two spheres, each one of the same size carrying the same amount of charge, but of different sign. They are connected by a conducting wire, ...
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1answer
152 views

Electric field inside coaxial cable

I have a very long coaxial cable with a cylindrical core of radius $a$ that has negative charge density $\rho = -k/r$ where $r$ is the distance from the axis of the cylinder, and an outer shell of ...
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0answers
23 views

When is force of interaction maximum?

A certain charge Q is divided at first into 2 parts q and (Q-q). Later on the charges are placed at a certain distance. If the force of interaction between the two charges is maximum then 1)Q/q = ...
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1answer
16 views

Distribution of charge on isolated system?

An isolated solid metallic sphere is charged with +Q. What will be the distribution of their +Q charge on the sphere ? If it is conducting then the net charge resides on surface and if not the net ...
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0answers
18 views

What does relative permitivity of medium mean and what does it depend on?

Does relative permitivity have someting to do with the polarization of medium , like for example how in inside the capacitor magnitude of electric field would be less due to a smaller opposing field ...
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1answer
893 views
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2answers
25 views

Spherical Conducting Shells, Potential

When we have a spherical conducting shell and charge on outer surface of the shell then the potential inside remains constant i.e, kQ/R (R=radius). But say the inner surface of the shell is charged ...
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1answer
27 views

Things that must be considered when mass producing a capacitor [closed]

The question is to list four things that must be considered when a capacitor is chosen for inclusion in a circuit which is to be mass produced. Are there a specific set of four things? I've come up ...
3
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1answer
588 views

Why can't charge be in a stable equilibrium in electrostatic field?

I am reading Feynman's Lectures volume_II where he discussed the impossibility of the presence of stable equilibrium in an electrostatic field. There are no points of stable equilibrium in any ...
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1answer
36 views

Coulomb's law and electric field intensity [closed]

here is question and solution I can't understand why R_x= 4a_z please explain it detail! ;-(
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0answers
22 views

Please Can Anyone help Me to drive the equation for Electric Field Around a test Charge Around A uniform Ring. [closed]

Please can i get a mathematical relation for electric Field around a test Charge Lying in the region of influence around a uniformly Distributed Charged Ring .
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1answer
91 views

Basic concepts of electrostatics

How to deal with a grounded conducting sphere (I.e finding charge on it) in uniform electric field ? And if any two charged conducting spheres are in each other's electric field then will ones field ...
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1answer
145 views

How to calculate the electric energy caused by eletrostatic field stored in a region, given $V$? [closed]

I have problem in apply the rules to find the energy stored in free space here is the problem Find the energy stored in free space for the region $$0.002<r<0.003m,\quad ...
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0answers
31 views

Self Energy (Classical Electrostatics)

In classical electrostatics, the total energy is given by $W_T=\frac{\varepsilon_0}{2}\int_{\mathcal{U}}{\left|E(\vec{r}')\right|^2 \mathrm d\tau'}$ , while the interaction term is $$W_I = ...
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2answers
156 views

Two different electrostatic charges in rotation

It's a theoretical problem. I mean I drawn a circle and I consider this circle exist. I would like to understand how works this device composed of a circle and two charges: Two charges fixed on a ...
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2answers
227 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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0answers
16 views

the mathematical relation between dipole moment and frecquency

Is there any direct mathematical relationship between frequency and dipole moment and if so does it fit if there more than one electric field affect it?
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0answers
17 views

Time in Coulomb's law [duplicate]

If you have an electric charge somewhere and you make a new electric charge right now when do these electric charges start to interact with each other? is it immediately or it take some time ? how ...
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1answer
129 views

Potential at the surface of a conducting sphere near a dipole

An ideal conducting solid sphere of radius $R$ and center $O$ is brought near a dipole with a dipole moment of magnitude $p$. Let the center of the dipole be called point $C$, and let the tangent from ...
3
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1answer
8k views

Charge inside conductor

I know that the $E$ field inside a conductor is zero. What happens if I put a source of charge inside the conductor? Say the conductor was spherical centered on the origin and there exists a charge ...
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2answers
13 views

Electric potential energy of a charge

Potential energy is the work done by the particle against a conservative force. Isn't it? when a charge is fixed on a free space and then when we bring another charge from infinity to a distance r ...
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0answers
41 views

Charged conducting wire ring and Greens function

ρ(r) = q 2πa2 δ(r − a)δ(cos θ). If this is my charge distribution on a conducting wire ring. radius=a. I am attempting to show my electrostatic potential as an integral along the z-axis I started by ...
2
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2answers
3k views

The electric field of a conductive sphere containing a charge - grounded vs not grounded

Let's suppose we have a sphere but unlike theoretical ones it'll have some thickness say $\Delta r$ and inner radius $R$. What I was wondering about is how will it behave if we place some charge $q$ ...
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16 views

Multipole expansion of the electric field generated by an infinite charged plane

Take an infinite plate with uniform charge density, the classical problem that is usually solved with Gauss' theorem, to get that the electric field outside the plane, at a point $\boldsymbol r$ is: ...
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2answers
144 views

Help understanding the solution to a problem regarding kinetic energy of a group of point charges

The problem provided by my professor goes as follows: "Now consider a situation in which all charges are equal to q and they simultaneously become "unglued". What speed will each charge have when a ...
3
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1answer
244 views

Basic electrostatics - Poisson's Equation

I would like to solve Poisson's Equation for a space charge region (fixed and free charges) that is located within a device of semiconductor material. Unfortunately I do not have any boundary ...
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1answer
30 views

Total potential energy in electric field?

if there are 2 charges generally potential energy of the system should be the sum of individual potential energy. but why the potential energy is half of the sum of every individual charge's potential ...
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2answers
147 views

Current in discharging capacitor through fixed resistor?

In the textbook I'm using for physics it says that the charge left on the plates of a capacitor after time $t$, that is discharging through a fixed resistor, is $Q=Q_0e^{-t/\tau}$ where $\tau=RC$ is ...
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1answer
26 views

Does a conductor in an external electric field have a positive charge density and electric field inside?

I'm thoroughly confused by conductors. Let's say you have a round(ish), perfect conductor. Solid and uncharged. Some distance from it, we place a point charge $q$, giving rise to a field $\vec{E}$. ...
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1answer
46 views

How and why do electric fields occur when we put a voltage difference between two point?

When we put a voltage differences between two points on a certain sample, I would like to know how and why the electric field occurs. In addition, I would like to know in what shape does the electric ...
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1answer
149 views

Why does the charge on the outer surface cancel the external field inside a conductor having a cavity filled with certain charge?

Let us take an arbitrary conductor having a weird-shaped cavity inside it. Let $+q$ charge be inserted inside the cavity. The field of $+q$ attracts negative charge & repels positive charge; ...
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0answers
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Method of image charges — Why is a *grounded* plate needed?

In the classic image charge problem of a charge $q$ above an infinite grounded plane, it is well known that the field lines essentially behave as though there were a negative charge behind it, and the ...
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0answers
27 views

When deriving potential between plates of parallel plate capacitor, why isn't the charge distributed on the top *and* bottom of both plates?

Let's say we have a canonical parallel plate capacitor with area $A$ and separation $d$ where $A>> d^2$. A charge of $+Q$ is placed on the top plate and $-Q$ is placed on the bottom plate. We ...
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2answers
29 views

Electric field Intensity , parallel plates

My book says that the electric field due to infinite long plates doesn't depend on 'r', so does it mean that no work is done in moving a point charge towards or away from it? Also considering the ...
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0answers
12 views

coaxial capacitor potential calculation

How is capacitance of a cylindrical capacitor calculated? In his question his Equation 1 tells us how to calculate the potential of a cylindrical object and there are two locations where I cannot ...
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4answers
214 views

How to calculate the work of the electrostatic forces in a parallel-plate capacitor?

The expression of the energy stored in a parallel-plate capacitor is: $$U = \frac{e_0\cdot A \cdot V^2}{2d}$$ with $e_0$ the vacuum permittivity, $A$ the surface of the capacitor, $V$ the applied ...
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1answer
25 views

Local charge density manipulation of ionized air

Assume we have ionized the air in an isolated container. Would is be possible to concentrate the ions within a specific region of the container with electric fields, i.e. to manipulate local charge ...
2
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1answer
248 views

Electric field in space created by intersection of spheres of charge

I am trying to calculate the electric field in space created by a body assembled by the intersection of 2 spheres. The upper sphere, its center is at $$\frac{d}{2}\mathbf{\hat{z}}$$ with radius $R$ ...