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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Is it possible to avoid static electricity? [closed]

Sometimes I touch a car or a door and I feel the static electricity in my hand and it hurts sometimes. I try not to touch anything because I feel like I am going to feel this pain again. Is there a ...
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2answers
96 views

How does a point charge interact with a Gaussian surface?

A spherical Gaussian surface encloses a point charge $q$. The point charge is moved to to a point away from the center of the sphere. Does the electric field at a point on the surface change? ...
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42 views

Why is the electric potential of a point from a point charge of +Q positive?

According to the formula, $$V = - \int \vec E \cdot d\vec r.$$ The electric potential of a point charge is $\frac{KQ}R$? However, when I perform the integration, my answer is $-\frac{KQ}R$. Since ...
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0answers
39 views

How did I get these strange electric shocks? [closed]

While doing experiment on designing & fabricating temparature controller circuit using a thermistor, this strange thing happened.Me & my friend frequently experienced short pulses of electric ...
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2answers
811 views

Why does electric force depend on the medium?

Comparing the equations for the gravitational and electric force $$\vec{F}_g=-\frac{Gm_1m_2}{r^2}$$ and $$\vec{F}_e=\frac{Kq_1q_2}{r^2}$$ I noticed the only major difference between them is that ...
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1answer
160 views

Electric Potential due to Sphere when cavity is at arbitrary position [closed]

While doing practice question, I came across a question... A solid sphere of radius a has a cavity of radius b which has a uniformly charge distributed with density $-\rho$ and the remaining part ...
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2answers
43 views

How is electric field effected by loss of energy of charge?

Recently, I asked a question related to energy of a charge(This is the question). In one of the answers, in the comments section, I got an answer that the strength of the electric field is lessened ...
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0answers
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Coulombs Law on Quarks [closed]

As from opinion from others the question don't seem to be clear so I did some changes. What is 5.33... it is 5+0.3+0.03+0.003+.... this sequence does not ends. now if we have a ball and we need to ...
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3answers
103 views

If the entire potential energy of the charge is lost within the circuit, what happens to the charge?

This is a really confusing question for me. Suppose, there is an electric circuit. And, right near to the negative terminal of the battery, I place 3 bulbs, which would take almost all the energy of ...
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1answer
65 views

Figuring out the orientation of a dipole and its distance from a point charge

The problem assigned is this: A dipole is centered at the origin of a coordinate system, and a small charged sphere is some distance away along the perpendicular bisector of the dipole. The particle ...
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0answers
53 views

Gauss' Law and Electric Field Close to a Ball

So I've learned about Gauss' law and I have something in my head. Why does electric field that is very close to a ball is not close to infinity. Take a look at this image: As we can see, if we make ...
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1answer
34 views

boundary condition of electrical field

The boundary condition of electrical field is well known. $$ E^{\perp} _{above} -E^{\perp} _{below} = \frac{\sigma}{\epsilon_0}$$ Griffiths wrote that where there is no surface charge $E^{\perp}$ is ...
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2answers
97 views

Shouldn't atoms of the same element repel each other? [closed]

Shouldn't the same type of atoms repel each other due to electrostatic charge?
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1answer
174 views

Two concentric conducting shells connected by wire with modified Coulomb law?

This question is related to this one, but is a bit different. Consider two concentric and conducting spherical shells connected by a wire. Inner shell has radius $b$ and (unknown) charge $q_b$ while ...
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0answers
32 views

Surface bound charge density in dielectric displacement

In Griffiths, it derived that the electric potential caused by Polarization $\bf {P}$ is written $$V({\bf r}) = \frac{1}{4\pi \epsilon_0} \int_{\mathcal{V}} \frac{\hat{\gamma} \cdot {\bf P}{({\bf ...
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4answers
405 views

What will be final velocity of three charges $q$, $q$, $2q$? [closed]

What will be final velocity of three charges q, q and 2q kept along an equilateral triangle of side r at infinite distance. All three masses are equal. I tried to conserve Total Energy ...
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1answer
64 views

Parallel plates with differing charges

I'm given a problem involving two parallel conducting plates a small distance apart. One has charge Q, the other is neutral. I'm asked to find the surface charges on all faces. I began by ...
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1answer
101 views

Mass of a point charge [closed]

A point charge is defined as an electric charge at a mathematical point with no dimensions(Wikipedia: https://en.wikipedia.org/wiki/Point_particle#Point_charge). Can anything be said about its mass in ...
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2answers
42 views

If protons(positive charges) also flow in a circuit, do we say that a conductor has free protons?

This might be a stupid question, but it is logical. We say that even protons or positive charge can flow to constitute current. But, protons are present inside the nucleus of an atom. So, when we say ...
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2answers
71 views

Finding out the charge density (electrostatics) [closed]

A solution to the potential in the region $ -a < y <a$ , where there is charge density $\rho$ , satisfies the boundary conditions , $\phi = 0$ in the planes $ y = -a$ and $y = a$. $$ \phi = ...
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2answers
51 views

Which charge actually moves to constitute current? Positive or negative?

Now this might be a very stupid question for many readers, but I am getting really confused. I was reading about electricity and current, and I read this: Suppose we connect a wire to the ends of a ...
2
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0answers
24 views

Symmetry arguments and plane sheet of charge [duplicate]

The electric field due to a infinite plane sheet of charge is given by $\sigma/\epsilon_o$. Now could we have deduced by symmetry that the electric field's magnitude won't depend on distance?
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3answers
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Do we know why the field produced by charge extends to infinity?

Do we have any model to show why charge field or magnetic field extends till infinity. Edit: I agree that according to coulombs law $1/r^2$ cannot be 0 but do we know why this happens.I think I am ...
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1answer
41 views

Charge outside a Sphere given charge density

If a sphere has a charge density of $\rho =\alpha r^2$, I want to calculate the Electric field outside of the sphere. Starting with Maxwell's equation $\bigtriangledown\cdot E=\frac{\rho }{\epsilon ...
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1answer
49 views

Electrical work and Coulomb's law

In some text books I've encountered the calculation of electrical work done on a point charge moving in an electric field (e.g. when demonstrating that electric force is conservative) is done by ...
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1answer
79 views

Electrostatics: Cylinder and conducting plane question (method of images)

I was looking at some problems/questions about electrostatics and came across this question: An infinitely long cylinder of radius $a$ and with charge density per unit length $\lambda$ is placed ...
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2answers
37 views

What is the meaning that electric charges flow from high to low potential till both acquire same potential?

I was reading about electric current and circuits. I read in my book that electric current is caused when charges flow from high potential to low potential till they both acquire same potential. So my ...
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2answers
78 views

Some confusions regarding electrostatic shielding

A spherical conductor A contains two spherical cavities as shown. The total charge on conductor itself is zero. However, there is a point charge q1 at the centre of one cavity and q2 at the centre ...
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1answer
39 views

$\mathbf{J}$ and $\mathbf{E}$ having the same direction [closed]

Ohm's Law States that $\mathbf{J} = σ\mathbf{E}$ this implies then that $\mathbf{J}$ and $\mathbf{E}$ have the same direction . But we know that $\mathbf{E}$ in normal to a conductor and $\mathbf{J}$ ...
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1answer
57 views

Saving energy while charging capacitor

While charging a capacitor by a DC source, half energy is wasted as heat. Can't we save that energy? Here I am talking about $$1/2CV^2 $$ which is wasted while supplying $$CV^2$$
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0answers
124 views

Calculating potential energy per ion of an one dimensional ionic crystal

The problem states to calculate "the potential energy, per ion, for an infinite 1D ionic crystal with separation $a$"; the crystal is a 1D lattice of alternating charges, likes so: ...
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1answer
43 views

Definition of Charge [duplicate]

Please give me a definition of charge. A textbook I have defines it to be - "A fundamental property of matter, which determines whether the matter will receive an electric flow or liberate one" I ...
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0answers
43 views

A question in electrostatics

The following is from Problems and Solutions on Electromagnetism. The electrostatic potential at a point $P$ due to an idealized dipole layer of moment per unit area $\pmb {\tau}$ on surface ...
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1answer
72 views

A question when using $E= - \nabla V$

This problem is from Problems and Solutions on Electromagnetism. A thin but very massive disc of insulator has surface charge density $\sigma$ and radius $R$. A point charge $+Q$ is on the axis of ...
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1answer
45 views

How can we verify the direction of electric displacement is radial?

I have two questions about electric displacement $D$. The following is a problem in Griffiths. A long straight wire, carrying uniform line charge $\lambda$, is surrounded by rubber ...
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1answer
49 views

Why is there no electric potential energy when it is directly above an electric dipole?

If you have two opposite charges of equal magnitude, why is the potential energy of another random particle that is directly above or below the middle distance between the two charges have 0 electric ...
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4answers
57 views

Same equation, different meanings

I went into a physics classroom today and saw this equation written on the board: $$ E = \frac \sigma \epsilon $$ At first I thought it referred to the electric field $ E $ between 2 parallel plates ...
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1answer
14 views

Why are pressure/potential differences across a barrier measured from inside to outside?

I don't know if I'm asking clearly, but I'm a Medical Student who is trying to intuitively understand pressure differences and electrochemical gradient (across a semipermeable membrane) differences. ...
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4answers
144 views

Charge inside a charged spherical shell

If I were to put a negative charge inside a negatively charged spherical shell, will it move to the center? Electric field inside the shell due to the shell is zero (Gauss's Law), would that mean ...
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0answers
30 views

Series expansion of potential due to a dipole displaced from the origin

I learn that we can expand the electric potential in an infinite series of $\rho$ and $\cos(n \phi)$ when solving the Laplace equation in polar coordinates. The problem I want to consider is the ...
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0answers
50 views

Where to place a charge to establish net force of 0? [closed]

A charge, Q2 = -15.00x10^-6 C, is 10.00 cm to the right of charge Q1 = 18.00x10^-6 C. Where can a third charge be placed, along the line connecting Q1 and Q2, such that it experiences no net force ...
2
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2answers
65 views

How do two metal balls of radius $r$ kept at a large distance form a capacitor? [closed]

So this is something really new to me. I have learnt of plate capacitors, cylindrical capacitors, single spherical capacitors, etc. but that to, of finite distance between them. Also please explain if ...
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0answers
137 views

distribution of electric charges

In electricity courses, in the lesson on static fields, at some point all teachers say "let's consider a large rectangular metal plate where the density of charges is uniform", and then they proceed ...
5
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2answers
119 views

metal die charged, where do the charges go?

I'm puzzled by this question: I have a metal die (a regular cube, completely filled with homogeneous iron for instance); I charge it with some µCoulombs. Where do the charges go? Can the faces of the ...
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1answer
131 views

Atoms, Gravity and Electrostatic Charge [closed]

How close do 2 atoms of any type the have can be together before gravity with an electrostatic charge that repulses?
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0answers
46 views

Electric Field at a point some distance above a uniformly charged cylinder

In this problem I am trying to solve, I am trying to find the electric field at a point directly above a uniformly charged cylinder. The cylinder is oriented so that the two round face are parallel ...
3
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0answers
43 views

Why is the susceptibility $\chi(t)$ real?

So my question is quite simple I suppose, and perhaps trivial. It is known that the frequency domain susceptbility $\chi(\omega)$ is complex, and that the two parts can be related with the ...
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1answer
34 views

Relation between dipole moment and polarisaton

In the Landau's book "Electrodynamics of Continuous Media" he derives the relation between the polarisation $\vec P$ and the dipole moment $\vec p$. Starting with the definition of the dipole moment: ...
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1answer
51 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
40 views

Understanding of dipole moment and its vector property

I have a trouble understanding the electric dipole moment. The electric dipole moment formula is $${\bf p}= \int {\bf r}' \rho({\bf r}')d\tau '$$ I'm interested in the coordinate, the origin of which ...