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 [tag:magnetic-...

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Why Electrostatic field has a continuous curve?

An electrostatic field line is a continuous curve. That is, a field line cannot have sudden breaks. Why not ?
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43 views

Azimuthally Symmetric Potential for a Spherical Conductor

I am trying to solve problem 2-13 from my textbook "Principles of Electrodynamics" (see image below). I believe that I should be solving the potential as $ \varphi(r,\theta) = \sum_{n=0}^\infty (...
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63 views

Potential of ring of charge and a conducting sphere

My goal is to find an expression for the expression of the force on a conducting sphere due to a circular ring of total charge $Q.$ The sphere has radius $a,$ and it is placed along the axis of the ...
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14 views

Calculating pressure on a dielectric kept inside a capacitor

Firstly, the pressure is because of the opposing forces acting on both sides of the dielectric slab. On the left side of slab, the field due to the left plate is $\frac{\sigma}{2\epsilon_0}$ and that ...
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2answers
29 views

smallest possible length of copper wire, where I can measure capacitance via multimeter [closed]

I am a new highschool physics instructor and I want to show to my students the basic concept inside the capacitors. i plan on showing them via simple 2 copper wires side by side each other, supplied ...
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1answer
71 views

Will a permanent dipole placed in a uniform external electric field exhibit periodic motion if it is displaced from equilibrium position?

Because at equilibrium position, the dipole is aligned along the direction of electric field and since it is a uniform electric field ,there will be no force on the dipole but it can still experience ...
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1answer
34 views

I have a doubt in finding workdone by a negative charge in moving it in presence of positive charge

Let say I have a positive charge at the origin. Now imagine I get a negative charge from $X=10~\text{cm}$ to $X=2~\text{cm}.$ By common sense we can say that the work done by us will be negative as ...
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1answer
49 views

Auxiliary magnetic field identically zero?

Consider a 3D space that's filled up completely with a material of fixed magnetization $\mathbf{M}$ (i.e. everywhere in space the magnetization points in the same direction and has the same magnitude)....
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1answer
41 views

Is electric potential a field?

I'm just learning about electric potential in my second-semester physics class. My textbook is emphasizing the fact that electric potential is a property of the source charges and that I'll soon learn ...
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2answers
628 views

Principle behind electrostatic shielding?

If we have a solid conducting sphere with charges around it, then the electric field inside the sphere is zero, otherwise the electrons of the sphere would not be in equilibrium as there would be a ...
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1answer
77 views

How can charge be squared?

In many Wikipedia articles I have come across it refers to a Coulomb squared. What does this mean intuitively? i.e. http://en.wikipedia.org/wiki/Farad (this was the most recent place I came across ...
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38 views

In terms of work, what happens to a negatively charged particle circling around a positively charged rod?

Picture a positively charged glass rod from its end so that if you were to draw it on paper, it would appear as a circle. Now, suppose a negatively charged particle moves in a circular arc, on the ...
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2answers
4k views

Can sugar be affected by a magnetic field?

While I was making a morning coffee at work, some sugar from the spoon started to fly away, seemingly towards some foam cups. Can this be explained by magnetism?
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50 views

Two spheres (one positive, one negative) - electric field

I posted yesterday about a problem I had and I have managed to solve one of the two I think (Here is the original post: Dielectric field in a homogenous electric field ). I didn't want to edit the ...
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0answers
16 views

When two equally opposite charges placed then which type of motion will carried out b/w them? [duplicate]

I want to know that which type of motion will carried out between two equally opposite charged particles, when they placed in front of each other.
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2answers
55 views

Inconsistency with electrostatic energy formulas

The energy of point charge configuration can be written as: $$W = \frac{1}{2}\sum_{i=1}^{n}q_{i}V(r_{i}) \, ,$$ which can take both positive and negative values. However, when we integrate the ...
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2answers
136 views

What does “charge” actually mean? [duplicate]

I know that a charged particle is defined as a particle that experiences a force in an electric field, as explained in this post: What does a subatomic charge actually mean? However, I still don't ...
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1answer
178 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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2answers
54 views

Filling a charged capacitor with dielectric material

If there is a charged capacitor (capictance $C$) connected to a battery (of EMF $V$) and the space between the plates of the capacitor is filled with a dielectric material (dielectric constant is $K$),...
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1answer
48 views

Time dependent electric field: Mathematical expansion for local electric field

In many articles and books I see that local electric field is expanded as $$\vec E_0(\vec r(t)) = \vec E_0(\vec R_0) − (\vec a(t) \cdot \nabla) \vec E_0(\vec R_0) \cos(\Omega t) + \ldots $$ For ...
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3answers
117 views

What is the potential difference between $a$ and $b$ in this basic circuit, when the switch is open? [closed]

My professor says the potential difference between $a$ and $b$ is the difference between the voltages on the top left capacitor and the bottom right capacitor. My friend and I however both think it's ...
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0answers
37 views

Why is the energy lost due to the internal resistance always equal to $(1/2)CV^{2}$ in a simple capacitor battery circuit? [duplicate]

Suppose we have simple circuit in which a battery of EMF $E$ is connected to a capacitor of capacitance $C$. Work done by battery $W_{b}=CV\times V$ and energy stored in capacitor $=\frac{1}{2}CV^{2}$...
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1answer
70 views

Force on a charged particle due to an uncharged infinite conducting plate

How can I calculate the force on a charged particle due to an uncharged infinite conducting plate? If there is a small object with positive charge placed above a metal plate, the object induces a ...
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4answers
978 views

The maximum distance for which Coulomb's law has been verified?

We know that Coulomb's law, $F_{12} = \frac{kq_1q_2}{r^2}$, was experimentally verified for small distances by Coulomb himself at the and of the XVIII century. The question is what is the maximum ...
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2answers
41 views

When two coils carrying opposing currents are placed coaxially

The current flowing through these coils increases in this case according to the book. But it does not clearly state how. This is what it says: "When brought closer induced effects should produce ...
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2answers
174 views

Is Coulomb's law valid if the electric charge is not constant in time?

If the electric charge is constant the law of Coulomb says that: $E(r) = kQ/r^2$. The question is, if $Q = Q(t)$, can I consider that: $E(r,t) = kQ(t)/r^2$? Update: It appears that the first ...
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2answers
61 views

What does it means to say an electric charged person has a higher potential voltage compared to the door?

I'm studying electric potential energy and its defined as the energy needed to move a charge inside an electric field from a point $a$ to $b$. Then, it defines electric potential energy per charge, ...
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2answers
267 views

How electrical energy is transfered trhough a wire, and what's flow of charge?

I've read these texts about misconceptions about electricity. This is my understanding: Electrons do move, mut slowly and randomly. What happens is that, in fact, they're just 'conducting' the ...
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0answers
39 views

Uncharged metal rod brought near a charged electroscope. Why does divergence of the leaves decrease?

Could someone please explain the redistribution of charges (if any) in a charged conductor that is being used to induce charge on another conductor?
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2answers
57 views

Thought experiment and faraday cage

this is my first and second questions. I'll start with my assumptions and go from there to ask my questions. Please do not hesitate to correct me if any of these assumptions are wrong. Inside of a ...
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1answer
57 views

The force applied by two charges on each other when there is another charge nearby them

QUESTION 1 Let me give two simple scene of charged particles to make you understand my question. There is a fixed positive charged particle in the center. Scenerio 1 : A fixed negative charged ...
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1answer
59 views

Does an observer measure magnetic field when moving inside a static E field?

Imagine a static electric field shaped as a sinusoid created by an array of electrodes on an infinite line. Does an observer flying parallel inside this e-field measure an h-field ?
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31 views

derivation of the electic displacement D

I've been revising Maxwell equations recently and tried to prove that the electric displacement $ \mathrm{\nabla \cdot D = 0}$ in the electrostatic approximation ($\mathrm{E = - \nabla} f$). My steps ...
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1answer
43 views

Where does the net charge on a hemisphere appear to act from?

I was wondering if, like centre of mass, there is anything called "centre of charge".
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2answers
500 views

Electric Potential, Work Done by Electric Field & External Force

I did lot of searching but couldn't find any textbook nor any webpage which could clarify my doubt. Maybe my doubt is insanely stupid and I was dumb for not realizing it at the first place. The ...
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0answers
86 views

dielectric polarization

Suppose a small solid sphere made of an isotropic dielectric is introduced in the field of some given system of remote charges. Assuming that the polarization in the dielectric does not affect the ...
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0answers
67 views

How much electric charge can a copper sphere, made of N atoms, contain?

If somebody wants to charge a cooper sphere made of N atoms, what is the maximum positive charge the sphere can reach? Same question about a negative charge. Source For example if the sphere is ...
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2answers
83 views

Simple model that explain the flow of electrons in metals

I am not quite clear about how electrons (negative electric charges in general) flow through a metal. I imagine the metal as a lattice of small positive charges $+q$ that can not move and the - and + ...
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2answers
90 views

Divergence-free vector field on a non-simply connected domain

We know that divergence-free vector fields are themselves curls of vector fields on simply connected domains. I want to construct a counterexample in the case the domain is not simply connected. So ...
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2answers
56 views

Why can we replace a cavity inside a sphere by a negative density?

I have a sphere with radius $R$ and inside this sphere there is a smaller sphere with radius $\frac{R}{3}$. This small cavity has its center at $\frac{R}{2}$, it doesn't matter in which direction. If ...
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1answer
40 views

Integration path with opposite direction from the unit vector

The task is to calculate the voltage between points $M$ and $N$ if the electric field vector is known to be $\vec{E}=\frac{V_0\cdot x^2}{a^3} \cdot \vec{i} + \frac{V_0 \cdot y}{a^2} \cdot \vec{j}$, ...
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2answers
93 views

Electric field and electric scalar potential of two perpendicular wires

So, I've been trying to come up with an idea that seems plausible to me for the last half week or so, but I'm stuck and I can't seem to get anywhere with this problem. The problem is as follows (...
1
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1answer
53 views

Two points in a charged hollow sphere with zero potential difference

Two concentric spheres (I've provided a simple sketch below) with radii $a$ and $b$ are given. The space between two spheres (colored yellow) is charged homogeneously, meaning that the charge density ...
2
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1answer
76 views

Is Gauss electric flux law valid in all coordinate systems?

The derivation of Gauss electric flux is as follows : $$\iint{\vec{E}}\cdot{\vec{dS}}=\iint E \, dS \cos\theta \, .$$ The projection of infinitesimal area on the surface $\vec{dS}$ on the radial ...
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2answers
852 views

Why are potential differences equal across two capacitors in parallel, but charge on each capacitor is not?

Two or more capacitors are said to be connected in parallel if each one of them is connected across the same two points. In a parallel combination of capacitors potential difference across each ...
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0answers
21 views

How to understand Steady Currents within the limits of Magnetostatics

I know that the precise mathematical statement of local charge conservation is $\nabla \cdot \vec{J}=-\frac{\partial \rho}{\partial t}$, where $\vec{J}$ is the volume current density and $\rho$ is the ...
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0answers
32 views

Electric Field from a distribution of charge

We have a thin flexible rod bearing charge $Q$ of length $L$. This is bent into a semicircle. Find an equation for the electric field in terms of $Q$, $L$, and appropriate constants at the point ...
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1answer
56 views

Image charge distribution for an infinite non conducting plane

If I have a charge +q at a distance d above an infinite non conducting plane, why should the image charge at d below the non conducting plane be +q?
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1answer
29 views

Dipole moment of a displaced charge distribution [duplicate]

This one is part b) of the problem I asked a day ago. Special thanks to MarkMitchison and sbp on the first part. I finally got it. (How can I prove that the dipole moment is zero?). Alright, back to ...
0
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0answers
72 views

Spherical Conductors in Dielectric - Potential

I have computed the electric field of the following system between the two spheres, but my calculations for the potential do not make sense. The potential should be proportional to $\frac{1}{r}$ but I ...