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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Conductors, charges and method of images; Intuition?

Two charges e and -e are placed at distances d and 3d, respectively, above an infinite conducting plane (directly above one another). Find the force on the charge e. To Solve this I consider another ...
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1k views

Capacitance of spherical capacitor when earthed

The capacitance of a spherical capacitor is given by $$C=\frac{4\pi \varepsilon_{0}}{\left ( \frac{1}{a}-\frac{1}{b} \right )}$$ How can I find out the capacitance of the capacitor when The ...
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1answer
25 views

Understanding zero field inside a conductor?

Imagine a neutral conductor of any shape, the charges are randomly distribuited among the object. No way we can say the electric field inside is zero. If I'm wrong, then what can we say about the ...
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1answer
15 views

Which way is the magnetic field headed? [closed]

Question Is the magnetic field directed into the page or out of the page? I am using this right hand rule --> RHR So anyhow, my index finger is pointing downwards, and since the magnetic force is ...
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1answer
266 views

Electric field in space created by intersection of spheres of charge [closed]

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 $R$ ...
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0answers
41 views

What is the charge density for line and surface charges?

In electrostatics it is common to see line, surface and volumetric charges being described differently. A line distribution is a function defined on the line, a surface charge distribution is a ...
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1answer
428 views

The image current due to moving charges and a current carrying thin wire

Suppose we have a plane conductor and positive charged particles of mass m are moving parallel to the plane conductor at a distance d. The trajectory can be assumed to be straight. An image current ...
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1answer
586 views

Finding Green function using eigenfunction expansion method

Given the Dirichlet boundary condition, I am to show that the functions that satisfy $$(\nabla ^2 + k_{lmn}^2) \psi_{lmn} (x,y,z) = 0$$ are given by $$\psi_{lmn} = (\frac{\pi}{2x})^{1/2} ...
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0answers
33 views

Expressing charge density in terms of spherical multipoles

How to express the charge density in terms of the full set of the spherical multipole moments? That is, how to invert the relationship $$ Q_{lm}=\frac{4\pi}{2l+1}\int ...
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58 views
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1answer
22 views

Is there a charge difference between ground and our head?

I commented on a question on Skeptics.SE that it would be an interesting question whether there is a charge difference between ground and our head. The question is not very relevant, but here it is ...
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1answer
152 views

How can electric field representation be obtained from Enge representation using Maxwell's equations?

Suppose we have a long electric capacitor. Let $L$ be its length ($z$ coordinate), $W$ its width ($y$ coordinate), and $D$ its full height (full aperture; $x$ coordinate). Let $L\gg W\gg D$. The ...
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1answer
40 views

Force of Electrostatic Attraction between 2 rings

Before someone puts it on 'hold' , this is not a homework question, I doubt you'll find it somewhere as I thought of it. I wish to find force of electrostatic attraction between 2 uniform rings of ...
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1answer
141 views

What is the strength of the magnetic field required to penetrate an average human body?

Introduction Suppose you are an experimental nanobot researcher trial-ling a new form of medication that involves activation and control of nanobots within the cells of the interior of the human body ...
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3answers
388 views

Why does the Electric Field of a dipole have no $x$ component?

According to the solution $2E\sin(\theta) = E_{net}$. I understand how the dipole works but I don't understand why the x component would be 0?
2
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1answer
307 views

Force due to combination of free space and dielectric

I will make a generalized form of my question. There are two point charges $q$, $x$ distance apart. And there is a dielectric slab of thickness $t$ and of dielectric constant $K$. Should the force ...
1
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1answer
31 views

Immersing a copper sphere into a conducting liquid that is itself in a conducting bath [closed]

Question A small copper sphere of radius a is half immersed at the surface of a poorly conducting liquid of resistivity $\rho$. The liquid is contained in a spherical copper bath of radius b, where b ...
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1answer
144 views

Charge distribution on a Gaussian surface

In the text, it is said that the skewed distribution of positive charge on the inner wall cannot produce an eletric field in the shell to affect the distribution of charge on the outer wall. Why? ...
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2answers
26 views

Electric Flux in a Gaussian Surface

Why is electric flux of a charge everywhere inside a Gaussian Surface constant? I want explanation ( not from any equation ).
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30 views

What is the relationship between potential energy and electrical potential?

I actually always thought this was trivial, now I am not so sure. For a potential $\phi$ the potential energy is $V=q\phi$ where q is a test charge. Now I am thinking this may work differently in two ...
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1answer
226 views

Electric field inside two parallel lines of charge

At what force will a particle be subjected to inside two parallel line charges with the same length and charge density. I get that in the middle the forces will cancel, but will they cancel if the ...
2
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1answer
56 views

Dipole moment of a single point charge

Kindly refer to the Multipole Expansion section (chapter 3) of David Griffith's Introduction to Electrodynamics. Let us first discuss about why multipole expansion is needed. As far as I understand, ...
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1answer
41 views

While deriving Coulomb's Law from Gauss' Law, the power of 'r' comes out to be exactly 2 while experiment shows that it differs about 10^(-16). Why?

While deriving Coulomb's Law from Gauss' Law, the power of 'r' comes out to be exactly 2 while experiment shows that it differs about 10^(-16). Why is it so? I'm referring to the book 'Physics by ...
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1answer
43 views

Coulomb's law and its application [closed]

I just read that Coulomb*s Law describes (a) the forces that bind atoms together to form molecules (b) the forces that bind molecules together to form solids. My question is Do a proton share ...
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2answers
157 views

Does charge of a metal charged by induction determine by which ends of the metal is grounded to?

Does charge of a metal charged by induction determine by which part of the metal is ground to? I draw a diagram to make it simple to understand: Right diagram: When ground is touched with the ...
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2answers
57 views

Calculating the surface integral over a charged box [closed]

In a question that I'm trying to solve, we're told that there is a box with dimensions 20cm long, 4cm high, and 3cm deep. we're given that the electric field on every surface of the box is pointing ...
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0answers
42 views

Calculation of charged sphere distribution near a wall in Cartesian coordinates

I am following a similar derivation as found in the beginning of this paper "Quantitative aspects of the growth of (charged) silica spheres" by A.P. Philipse. This paper calculates the growth of a ...
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1answer
19 views

Energy (voltage) correction on energy level between metallic electrodes with dielectric and accounting for work function difference

My goal is to understand how to correct for the field drop and the work function difference when performing electrical measurements on a certain energy level of a sandwiched system. The situation is ...
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1answer
33 views

Understanding electric potential in the context of gravitational potential?

I'm trying to understand the concept of electric potential and the significance of an electric field being related to the gradient/derivative of an electric potential. I found this question that ...
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1answer
322 views

Why does a point charge generate an electric field and why is an electric field represented by this formula?

Why does a point charge generate an electric field and why is an electric field represented by this formula $$E ~=~ \frac{q}{4 \pi \epsilon r^2},$$ where $\epsilon$ is permittivity of free space ...
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2answers
19 views

Net Electrical Force

If a metal is insulated from earth and if a charged object is held near one end of it but not touched , will the net force acting on the metal be zero ?
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2answers
36 views

I don't get the idea of potential in a capacitor [closed]

First off, what is meant by the potential of the conductors? Also potential difference between the two conductors is a function of distance from either right? Then why does it have an exact value. For ...
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0answers
28 views

Does a positive electric charge moves when it is placed inside a hollow conductor, but not in the center?

Electric Field inside a hollow conductor is zero. But what happens to a positive electric charge put inside.
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2answers
67 views

Can a grounded spherical shell have a charge?

Can a grounded spherical shell lying inside another bigger non-grounded shell have charge on it? If yes then why? Won't the charge on the grounded conductor flow to the ground?
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4answers
6k views

Potential difference between point on surface and point on axis of uniformly charged cylinder

Question: Charge is uniformly distributed with charge density $ρ$ inside a very long cylinder of radius $R$. Find the potential difference between the surface and the axis of the cylinder. Express ...
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1answer
23 views

How does electric charge flow in the typical experiment of scuffing your shoes across the carpet?

I'm trying to understand the flow of electric charge. I have read about the triboelectric series, but I do not know where the rubber soles of shoes and carpet reside to know whether the shoes acquire ...
2
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3answers
197 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 ...
3
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2answers
50 views

Electric field inside a material

I was thinking about the polarisation, and how the electric field behaves inside the material of permittivity greater than one. I think to have understood what happens to D and P, but is not clear ...
1
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1answer
26 views

Surface charge distribution on a conductor derived by method of images techniques

Kindly refer to "The classic image problem" of "THE METHOD OF IMAGES" of Introduction to electrodynamics book by Griffiths (Chapter 3). A point charge is placed at (0,0,d) on the z axis. The XY plane ...
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2answers
443 views

Capacitors in a series circuit with dielectric

When a dielectric slab is inserted between the plates of one of the two identical capacitors in Fig. 25-23, do the following properties of that capacitor increase, decrease, or remain the same: (a) ...
3
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1answer
44 views

Gauss law and electrostatic induction. Concentric spheres

Imagine you have hollow concentric spheres A and B with radius a and b (b>a), respectively. If A is a conductor and B has a certain density charge, I´ve been taught that B will induce some net charge ...
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1answer
26 views

Electric potential and work

A unit positive charge $q$ is placed in an electric field caused due to a positive charge $Q$. $q$ experiences force of repulsion $F_R$. We apply an external force (FEXT) opposite to $F_R$. The ...
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0answers
20 views

Charged metal sphere- electric potential [duplicate]

Why is the electric potential on the surface of a charged metal sphere always constant?
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2answers
67 views

Whats the meaning of this equation relating electric field and potential energy?

My electrodynamics teacher was explaining that it is required to apply some energy (or do some work) on charges in order to arrange them in space. When he stated an example about energy in a capacitor ...
4
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4answers
12k views

Why is the electric field perpendicular to every point on the surface of a conductor?

I am reading Berkeley Physics Course, Volume 2 (Electricity and Magnetism by Edward M. Purcell). I am in chapter $3$, page $92$, and the book discusses conductors. The following is from the book: ...
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0answers
26 views

Fourier Transform point force on a half-space [migrated]

I have to calculate the following Inverse Fourier-Transform, which describe the potential function for a point force on a half-space: ...
1
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1answer
272 views

Force and Energy of interaction of conducting sphere and point charge

A completely isolated neutral conducting sphere of radius $R$ is kept such that its center is at a distance of $r\left(>R\right)$ from a point charge $+Q$. How can I find the force of ...
1
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1answer
78 views

Electric Flux is zero

When is the Electric Flux zero through a closed surface? I know that if number of field lines entering is equal to leaving then it is true. Which I think is always true for a closed surface. So can ...
4
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4answers
369 views

Electric field on the surface of a charged sphere

We know that the electric field for a point charge is $$ E = \frac{KQ}{R^2}. $$ If $R$, i.e. distance from the electric field producer to the point where we want to find the electric field becomes ...
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1answer
40 views

electrostatics and elecrtic field [closed]

two opposite charges are placed and thee electric lines of forces are drawn if the angle made by the tangent at the initial point of one charge is 'a'then find the angle made by the line of force that ...