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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1answer
29 views

Electrostatics of hollow conductors

My textbook says: Inside a conductor, electric field is zero. The interior of a conductor can have no excess charge in static situation. Electric field just outside a charged conductor is ...
0
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1answer
33 views

Reduced electric field strength in dielectric

Under what conditions does the field due to free charge is simply reduced by factor of 1/k where k is dielectric constant? I.e my book says if dielectric is entirely ...
-2
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1answer
58 views

Why $\epsilon_0 = 1/(4\pi k)$ instead of $\epsilon_0 = 4\pi k$? [on hold]

In my physics book, they consider a positive point charge $q$ and a spherical surface of radius $r$ centered on this positive charge. Then the flux through this surface is given by $$\Phi = \iint \vec{...
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2answers
45 views

Formula for discontinuity of electric field across boundary

The formula for the discontinuity of the electric field across a boundary is given by$$\vec{E}_{\text{above}} - \vec{E}_{\text{below}} = \frac{\sigma}{\epsilon_0} \hat{n}.$$ In the derivation of this ...
0
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0answers
34 views

How to understand method of images in electrostatics without much maths

How do you explain Method of images for school students without much maths i.e without boundary condition or uniqueness theorem. If it's not possible what are the rules to be followed to solve ...
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votes
1answer
14 views

Can we use motor comb with metal sphere of Van de Graaff generator without belt? [closed]

Can we use motor comb with metal sphere of Van de Graaff generator without belt?
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0answers
36 views

What is Coulumb force at zero separation in classical picture [closed]

Assume a classical world. What would be force between 2 point charges if their separation tends to zero? Assume charges are static. My professor claimed it would be finite. I request you to ...
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votes
0answers
25 views

Electric Field around Uniformly Charged Rod [closed]

Question: A uniformly charged rod (length = $2.0~m$, charge per unit length = $3.0~nC/m$) lies on the x-axis. In consultation with your lecture notes, calculate the magnitude of the electric field at ...
1
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1answer
38 views

Effect of test charge on electric field intensity

Obviously on the macroscopic scale, having a test charge being a proton produces no noticeable change in the electric field produced by a charged body. However, on the microscopic level this would ...
2
votes
2answers
26 views

Charge distribution on a conductor surface

I understand that if a conductor was charged with a charge of say 1 coulomb, the charge would spread uniformly over it's entire surface to neutralize any difference in potential. However, and though ...
6
votes
1answer
181 views

Potential function - numerical simulation

Using MATLAB, I fixed the potential in a region inside a rectangular plate (100 V) and in the border (50 V). I got the following result of the potential along the plate: I can't find an intuitive ...
3
votes
1answer
55 views

Removing an electron from a conductor

I'm trying to understand how to think of and visualize a conductor where charge is added. As I understand, conductor are defined as materials (where the nucleus is stationary) that permit electrons ...
6
votes
2answers
57 views

Significance of electrical fields of infinite objects

I've noticed a pattern with the electric fields of charged objects of infinite dimensions. A point charge, which can be considered a charge of 0 dimensions, has an electric field that goes as $r^{-2}$...
1
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0answers
31 views

Discontinuity of electric field formula [closed]

I'm trying to understand where the formula for the discontinuity of an electric field when you cross a uniformly charged surface comes from: $$\vec{E}_{\textrm{above}} - \vec{E}_{\textrm{below}} = \...
0
votes
0answers
20 views

Electric field inside hollow metallic sphere which is not closed

Suppose I have a charged hollow metallic sphere. It is sure that the electric field inside the sphere is zero, in static case. ( I got explanation for this from the previous discussions in this site). ...
0
votes
1answer
15 views

System of point charges, work to move one of the systems point charge around

Suppose we have an electron at $\vec{x}_1=(0,a,0)$ and a proton at $\vec{x}_(a,0,0)$. Now i want to move the proton to the point $\vec{x}_3 = (0,0,0)$ and want to know how much work do i need for that....
1
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1answer
23 views

System of point charges, Potential related question

Suppose we have two point charges in the Cartesian coordinate system. $q_1= e, q_2 = 2e$, where $q_1$ is positioned at $(0,0,0)$ and $q_2$ at $(a,0,0)$ for $a > 0 $. Further there is a point charge ...
2
votes
1answer
49 views

Induced motional EMF where the wire is stationary and the field source is moving?

If a wire is moving in a magnetic field $B$, there is a Lorentz force acting on both the postive and negative charges, separating them to create an electric field, which is a great explanation to aid ...
1
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3answers
68 views

Intuitive explanation for uniform electric field between capacitor plates

Could anyone explain why the intensity of the electric field between plates of a charged capacitor is constant? Moreover, the varying the distance between plates doesn't change the electric field ...
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votes
2answers
60 views

What's the difference between $E=\frac{F}{q}$ and $E=\frac{kQ}{r^2} $? [closed]

Can $E=\frac{kQ}{r^2}$ only be applied to situations outside of parallel plates?
3
votes
2answers
53 views

Theoretical questions regarding the electric field

I found some theoretical questions in an old test of my school, and would like some help with the ones I cant answer: It is said that the electric field is an intermediary of the electric ...
3
votes
1answer
53 views

How to set up line integral of electric field? Confused over notation

In multivariable calculus the line integrals was parameterized and denoted: $$ \int_C \mathbf{F} \bullet \, d\mathbf{r}=\int_D\mathbf{F}(\mathbf{r}(t)) \bullet \frac{d \mathbf{r}(t)}{dt} \, dt $$ ...
4
votes
2answers
98 views

Why doped silicon does not undergo electrostatic discharge?

Doped silicon is charge neutral overall, but since the extra added carriers are only weakly bounded (~45meV) they become delocalized. Since the concentration of silicon is 5-9 orders of magnitude ...
1
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0answers
45 views

Refraction of the electric field lines, at the interface of separation between two conductive media

Suppose we have 2 media with electrical parameters ${\varepsilon _1},\,{\sigma _1}$, respectively ${\varepsilon _2},\,{\sigma _2}$, separated by the plane surface $\Sigma $; electrical charge surface ...
1
vote
1answer
44 views

Why don't charges build up on wires like plates of a capacitor?

Suppose you have a parallel plate capacitor and you want to charge it by using a battery. You will connect the plates with the two terminals of the battery. Now my book says that the charges will get ...
-1
votes
1answer
23 views

Connecting spheres of different capacitance

If I connect a sphere of capacitance $C_1$ to a charged sphere of capacitance $C_2$, will the charge be distributed evenly on both spheres (is the charge density going to be equal on both spheres?). ...
0
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0answers
34 views

Capacitance as integral of electric field [duplicate]

My question refers to part of Ex. 1.17 in Jackson, 3rd Ed.: A volume $V$ in vacuum is bounded by a surface $S$ consisting of several separate conducting surfaces $S_i$. One conductor is held at ...
1
vote
0answers
26 views

Why does static charge build up and how do I prevent it?

I bought my 11-month-old son a tricycle from Smart Trike (official website) and I have noticed that after a few laps indoors on my marble floors static charge would build up in him as I can see his ...
1
vote
1answer
36 views

Is a straight lightning bolt possible?

Recently, I saw a demonstration where an annealed steel rod and a hardened steel rod were made to fail from tensile stress (they were pulled on like an elastic band and snapped in a vice-like machine) ...
0
votes
0answers
16 views

Insulating cylinder with charge in a uniform electric field

Suppose that we have a very long insulating cylinder of radius $R$ on which we have placed some electrons such that it has a constant $\sigma_0$ charge per unit length. Assume that we then apply a ...
5
votes
3answers
184 views

How to show mathematically that the electric field inside a conductor is zero?

The electric field is characterized by the equations $$\nabla\cdot \mathbf{E} = \dfrac{\rho}{\epsilon_0}$$ $$\nabla \times \mathbf{E} = 0$$ Or equivalently, $\nabla^2 V = -\rho/\epsilon_0$ and then ...
-1
votes
0answers
26 views

What is meant by short circuit in capacitor?

I can't understand the mechanism of short circuiting in a capacitor. How will it come to know me that the capacitors are short circuited
1
vote
1answer
31 views

What is the method to find field at the center of a conducting shell due to induced charges due to an outside charge? [closed]

For example, if we had to find the field at Q1 due to the induced charges on the outside spherical surface ,what should be our approach? According to me, as the induced charges due to q2 on the ...
0
votes
2answers
38 views

On touching the negative terminal of battery, shouldn't this negative charge flow to earth?

On batteries one terminal is clearly mentioned as negative. I wonder can we neutralize this terminal by just touching it with finger? In electrostatics it is common to neutralize a charged object by ...
14
votes
3answers
950 views

How did physicists know that only negative charges move?

I have phrased similarly another question about how physicists knew that two charges exist, positive and negative. The purpose of the question is not necessarily to educate me historically. It's just ...
0
votes
1answer
88 views

Is the electric force a vector or a vector field?

The electric force (Coulomb's law) on a point charge $Q_2$ due to $Q_2$: \begin{gather*} \mathbf{F}_{12}=\frac{Q_1Q_2}{4\pi\epsilon_0}\frac{\mathbf{r}_2-\mathbf{r}_1}{|\mathbf{r}_2-\mathbf{r}_1|^3} \...
1
vote
1answer
37 views

Photon as a gauge boson for static fields

Excuse me if my question is naive, but I have never taken a proper QFT. I used to think of a photon as a quantum of EM field, quantum of light. But form QFT and particle physics prospective, photon ...
2
votes
1answer
25 views

Is potential difference the difference in electric potential energy or electric potential?

Referencing the book Physics for Scientist and Engineers, Ninth Edition, the book says that "Potential Difference should not be confused with Difference in Potential Energy." I also reviewed several ...
0
votes
0answers
31 views

Mistake calculating electrostatic potential energy formula!

I have a problem calculating the electrostatic potential energy. I rely on these equations coming from mechanics: \begin{equation} U_{B}-U_{A} = -W_{A \ \rightarrow \ B} (done\ by \ the \ field \ ...
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votes
1answer
49 views

Find the electric field of a uniformly polarized sphere

The problem statement, all variables and given/known data We want to calculate the field of a uniformly polarized sphere of radius=R Relevant equations $$V(\vec{r}) = \frac{1}{4 \pi\epsilon_{0}} \...
0
votes
0answers
41 views

A problem in Fourier transformation of Coulomb potential

Firstly, we calculate the Fourier transformation of $1/|\mathbf{k}|^{2}$ as follows, \begin{eqnarray*} \int\frac{d^{3}k}{(2\pi)^{3}}\frac{1}{|\mathbf{k}|^{2}}e^{i\mathbf{k}\cdot\mathbf{x}} & = &...
0
votes
1answer
25 views

Measurement of electrostatic induction

How is it with the electrostatic induction measurement? Everywhere you can read about the effect of electrostatic induction but I still can't found any detailed explanations or quantitative ...
36
votes
5answers
5k views

How did physicists know that there are two kind of charges?

Problems The question I am about to make is either too stupid or hasn't bothered anyone because its obvious because I can't really find the answer anywhere. I am currently studying electricity and ...
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votes
2answers
24 views

How to compute work needed to build a configuration of charges

Suppose an alignment of four charges in the vertices of a square. The first pair on one diagonal has positive charge and the other negative charge, all charges are of the same absolute value. length ...
2
votes
2answers
231 views

Symmetries of non-parallel infinite conducting planes

Suppose I have semi-infinite conducting planes that intersect at some angle $\theta_0$ and have a potential difference of $V$ (the axis of intersection is somehow insulated so they are not actually in ...
4
votes
4answers
204 views

Electric field dependence on distance

How can it be proved that for a point charge, $E$ is proportional to $$1/r^2$$ using the concept of Electric field lines (or lines of force)? I tried to show that if field lines are close, then ...
1
vote
1answer
11 views

Magnetizing a ferromagnetic material.

if i pass a DC current directly through iron or steel or something ferromagnetic, Would that magnetize that material? And would it be magnetized permanently? Another question, does anyone know what ...
1
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1answer
51 views

Name of electric force

during a lab experiment, i noticed that a metal ball has a much harder time rolling on metal rails when their is a current passing through it and the rails. I was wondering why and if there was a name ...
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votes
1answer
26 views

Electric field of a line charge, along itself

look at the pic : What is the electric field in along the line of charge with charge density $\lambda$ and length $L$. Is the electric field zero along the line without any difference in height?
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2answers
75 views

Discharging a capacitor

Suppose I have a charged capacitor, meaning there's a voltage (electric potential difference), say, $2V$, between its two plates. We don't know the electirc potential of the individual plates, right? ...