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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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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1answer
21 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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53 views

Is it almost impossible to separate two point charges stuck together?

$$F=k\frac{qQ}{r^2},$$ if $r\rightarrow 0$ then $F\rightarrow \infty$.
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1answer
35 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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0answers
24 views

What is the charge density for line and surface charges?

In electrostatics Poisson's equation allows us to find the electrostatic potential $\phi$ due to a charge density $\rho$ by solving the differential equation $$\nabla^2\phi = ...
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0answers
38 views

Electric potential inside a solid sphere [on hold]

We have charged solid sphere and have to find electric potential inside it. I tried it by two methods, By integrating $\int \vec{E}\cdot\text{d}\vec{r}$ for both outside and inside the sphere ( ...
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0answers
26 views

Where is the net electric field 0? [on hold]

A positive charge +3Q is separated by a distance, d, from a negative charge -Q. What is the closest distance in which the net electric field is zero.
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0answers
25 views

Force Of Attraction between 2 rings [on hold]

We have 2 rings of say equal radii (for simplicity) separated by a distance d. I ring carries +q charge and the other -q. I wish to compute the electrostatic force of attraction between these. Is it ...
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0answers
30 views

How to calculate the vector potential $A$ inside an infinite cylinder using Poisson's equation? [on hold]

Poisson's equation is : $$ \Delta \boldsymbol A = - \mu_0 \boldsymbol J$$ we want to calculate $\boldsymbol A$ inside an infinite cylinder with radius $a$ and the current density is $\boldsymbol ...
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0answers
19 views

Natural timer project

I want to make a light bulb that is already on, turn off after a time that is as close as possible to 30 seconds. However, I can't use an electronic clock timer. Essentially, I just need to make two ...
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2answers
15 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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0answers
28 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 ...
2
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1answer
38 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
38 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
20 views

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

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
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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7answers
1k views

Why is capacitance defined as charge divided by voltage?

I understand that capacitance is the ability of a body to store an electrical charge and the formula is $C=\frac{Q}{V}$. What I don't understand, however, is why it is defined as coulomb per volt. Of ...
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0answers
34 views

Self enery of a sphere [on hold]

If we have a sphere of radius 2R in which there is a cavity of radius R with concentric centre . Now we have to find self energy. I searched and got 3 methods : 1) U'' + U' + U* = U In this we ...
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2answers
46 views

Calculating the surface integral over a charged box [on hold]

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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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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0answers
26 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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1answer
18 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 ...
1
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1answer
25 views

electric charges on the surface and inside a charged body [on hold]

There is a hollow object (for example an inflated balloon.it is charged. where will the charges reside? Inside the balloon or on the surface of it? Why what will be the case of a solid sphere which is ...
1
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1answer
41 views

Coulomb's law and its application [on hold]

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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0answers
28 views

Gauss's law in three parallel plates [on hold]

There are three identical conducting plates with large surface area kept parallel to each other. The leftmost plate is given a charge Q , the rightmost a charge -2Q and the middle one remains neutral ...
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2answers
48 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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65 views
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34 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
14 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 ...
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1answer
17 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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0answers
29 views

Electron travel speed in spinning object [closed]

My question is in the hypothetical circumstance that you could spin a disk or something close to the speed of light how would that effect the travel of electrons through the material. Picture a circle ...
3
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2answers
48 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 ...
3
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1answer
35 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 ...
0
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1answer
25 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
19 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
65 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 ...
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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: ...
0
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0answers
28 views

Electric potential inside a conductor inside another conductor [closed]

Suppose there is a neutral hollow conductor body $B_2$ and there is another hollow conductor $B_1$ inside $B_2$ . Let there be a charge $q$ on $B_1$ . Let the potential inside $B_2$ but outside $B_1$ ...
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0answers
15 views

electrostatic seperator build questions [closed]

i am building an electrostatic seperator for plant material. the two materials i am trying to seperate have a negative charge but one responds a lot more to positve charges so i feel there will still ...
1
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1answer
69 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 ...
-1
votes
2answers
35 views

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

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 ...
-4
votes
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 ...
0
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1answer
20 views

Force on a charged conducting sphere due to a uniform electric field

If a charged conducting sphere is placed in a uniform electric field , will the force on it be simply qE ? I know that the electric field lines enter a conductor perpendicularly so does this have any ...
0
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2answers
30 views

Electric potential inside a shell

Inside a shell, electric field is zero. Then does it have a constant electric potential inside the shell? If $V=\dfrac Ed$, then since field is zero, potential should also have been zero. Please ...
0
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2answers
43 views

Electric Field Vector on an insulating solid ball

An insulating solid ball with radius $R$ has a uniform charge density $ρ$. Find the electric field vector inside and outside of the ball if it has dielectric constant $K$. Normally, I'd treat ...
1
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0answers
16 views

Wearing a metal had does, or does not, increase your chance of being struck by lightning?

Prompted by this video My view is that it makes no difference as to the conductivity of the head or the field strength around the head during a thunderstorm. OTOH, would an insulating hat reduce the ...
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0answers
23 views

How is corona discharge different from regular electricity ? [closed]

Since corona discharge is a electrical discharge is it any different from regular electrcity in terms of its ability to travel through wires, create magnetic fields , etc.
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3answers
60 views

Spherical Shell with Electric Field Zero Everywhere Inside It

If an isolated, charged spherical shell has a uniform charge distribution, the electric field everywhere inside it is 0, by Gauss' Law. Is the converse true? That is, given an isolated, charged ...
0
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1answer
29 views

doubt from capacitance and capacitors

Can a charged capacitor mathematically be represented as uncharged capacitor connected in series with battery of opposing emf ? Please explain with an example
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2answers
41 views

Potential Energy of Point Charges in a Square [closed]

So, an AP Prep book for the Physics 2 test has the following problem: My reasoning is as follows: The total potential energy = the sum of the PE of each of the 4 charges Which will equal 4x the PE ...