A fundamental and empirical law quantifying the electrostatic force between two charges.

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2
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1answer
47 views

Why do we take the value of the constant in Coulomb's law as $\frac{1}{4\pi\varepsilon_0}$? [duplicate]

Why do we take the value of the constant in Coulomb's law as $\frac{1}{4\pi\varepsilon_0}$?
-3
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0answers
27 views

Electrostatics coloumb's Law [closed]

The force of repulsion between two point charges is F, when these are at a distance of 0.1 m apart. Now the point charges are replaced by spheres of radii 5cm having the same charge as that of point ...
11
votes
6answers
563 views

What is the range of the validity of Coulomb's law?

What is the smallest and biggest distance in which Coulomb's law is valid? Please provide a reference to a scientific journal or book. Just saying that this law is valid from this range to that range ...
0
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0answers
14 views

Is there a simulator for observing the force between two charges comprehensively? [duplicate]

I basically want to observe the electrostatic force between two charges. I want to know if is there a simulator which could both help me to observe and calculate the force between two charges. I ...
0
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0answers
19 views

Is there a simulator for observing the force between two charges?

I basically want to observe the electrostatic force between two charges. I want to know if is there a simulator which could both help me to observe and calculate the force between two charges. I ...
5
votes
5answers
180 views

Is Coulomb's law accurate for moving charges?

Can we use Coulomb's law to calculate the force between two charges which are not at rest? If not, what formula should be used to calculate the force? I searched it, but I couldn't find a clear ...
1
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0answers
72 views

Why does Coulomb's law not hold for fast moving charges?

We all remember calculating the electric force of interaction between a stationary nucleus and a revolving electron using Coulomb's law. The electron in this case is moving. Here's what I think about ...
7
votes
1answer
151 views

Classical vs. quantum energy of the hydrogen atom

If I have an electron and a proton and calculate the classical energy which I get by bringing the electron from infinity to the distance of a Bohr radius to the proton, I get 27.2 eV, but the electron ...
2
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2answers
30 views

Electrostatics - Inserting a brass plate between two charges

The question is: if I were to insert a brass plate between two charges, what will happen to the force between the charges? Would it increase, decrease or stay the same? Does the brass plate increase ...
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2answers
99 views

The fundamental equations of electromagnetism

I'd like to know what are the basic equations of electromagnetism, that can be used to formulate all the other laws and equations. Those basic equations I can think of are Maxwell equations, Lorentz ...
0
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0answers
80 views

Has this approach to Coulomb force/Newton gravity unification ever been published?

Introduction: When toying with gravitational and electromagnetic equations in my undergrad days I stumbled upon this interesting relationship. With the very childish hopes of unifying gravitation ...
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2answers
131 views

Is it possible to calculate the force exerted by two unequal charge, separately?

According to the Coulomb's law, when two equal like point charges are placed 1m from each other the force between them is 9 * 109. But if two unequal like point charges are placed, the bigger charge ...
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0answers
56 views

Infinite chain of alternating charge

The problem There is an infinite chain (1d) of alternating charges that are in a distance a from each other. That is there is one charge +q and next to it -q and so on. Now calculate how much work it ...
0
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2answers
55 views

Could Charles-Augustin de Coulomb measure the charge in Coulombs?

Did Charles-Augustin de Coulomb know: Coulomb's constant Coulomb (as a unit) if not then what was the first time it was measured?
0
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2answers
90 views

How is $\text{PE} = qV$ derived using knowledge of $F = \frac{q_1q_2}{4\pi \epsilon_0 r^2}$

I recently started grade 11, and this concept confuses me, since if we place a charge $q$ on a potential $V$, I do not completely comprehend what values would need to be substituted which would give ...
0
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0answers
36 views

Dependence of Force as a function of Distance? [duplicate]

Why is the strength of a field (i.e. gravitational or electric) inversely correlated to the square of the radius? It is clear to me why the further you get a way from a field, the field's enacted ...
-1
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1answer
57 views

Attraction and repulsion of charge? [duplicate]

Why do like charges on identical bodies cause a repulsion and unlike charges cause an attraction?
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0answers
24 views

Electric Field: distributed uniformly in one infinity tape of length [closed]

One charge density surface is distributed uniformly in one infinity tape of length with $2a$ width from distance $d$. Determine the Electric Field in the point perpendicular from the distance $d$ ...
1
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1answer
29 views

Does higher voltage and plate area cause more separation between leaves in electroscope?

Does higher voltage cause more separation between leaves in electroscope? Will higher voltage and plate area attract more charge since Q = CV.
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2answers
157 views

Electrostatics kinematics equations (Coulombs Law)

If there are two similarly charged particles $Q$ and $q$ of masses $M$ and $m$, a Coulomb force is applied on each one (action-reaction). Suppose that $Q$ is stationary and we are shooting $q$ with an ...
0
votes
1answer
121 views

Electrostatics-Coulomb's Law

Coulomb's Law is an experimental result $$F=k_e\frac{q_1 q_2}{d}.$$ How did or What did Coulomb do to verify this law as it is applicable for point charges at rest and in reality charges won't be at ...
1
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0answers
38 views

How to prove Gauss's law div(E) = rho/epsilon from Coulomb's law? [duplicate]

As we know from coulomb's law that: $$\vec{E} = \frac{q}{4\pi\epsilon R^2} \hat{R}$$ using the above equation, how can I verify that: $$\vec{\nabla}\cdot \vec{E}=\frac{q}{\epsilon}$$ I have tried to ...
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0answers
32 views

Gauss law from Gauss divergence theorem [duplicate]

Apply Gauss divergence theorem to the gravitational field due to a spherical object of mass M and uniform density located at origin. Obtain Gauss law for gravitation in integral and differential ...
1
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1answer
162 views

Maxwells' equations and Coulomb's law

Coulomb's law and Maxwell's equations should be consistant as one can be derived from the other. Say we have a point charge with such a charge that $-kq=1$, meaning that at any point the electric ...
1
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1answer
115 views

Why Gauss' law is applied?

Why Gauss' law is applied? Why is there a need of finding electric field by Gauss' law if we can find the electric field through Coulomb's law? or has it got more applications than Coulomb's law?
3
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2answers
136 views

Relation between Gauss' law and Coulomb's law

In Coulomb's law if the relation was as if electric field intensity was to vary inversely $1/r$ with distance rather than the inverse $1/r^2$ of square of distance, would the Gauss's law still be ...
0
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1answer
122 views

Need for acceleration in particle-antiparticle annihilation? [closed]

If an electron and positron are accelerated towards each other, at distances quite far away, there wouldn't be any significant electrostatic attraction, hence they need to be accelerated. But when ...
0
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2answers
103 views

Who first verified Coulomb's Law for electron+proton interaction?

Who first verified Coulomb's Law for the interaction of a proton and electron? Was it Rutherford? Bohr?
0
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1answer
66 views

Reduced charge for attracting electrons?

The reduced mass in the two body problem is $\mu= \cfrac{m_1 m_2}{m_1 + m_2}$. Is there any analog to this with interacting charged particles (or at least that is of use somewhere in physics)? I have ...
12
votes
2answers
367 views

Why is there no permittivity-type constant for gravitation?

When I look at electric or magnetic fields, each of them has a constant that defines how a field affects or is affected by a medium. For example, electric fields in vacuum have a permittivity constant ...
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3answers
747 views

2 dimensional Coulomb's law equation

We can notice that in the Coulomb's law equation, $$\begin{equation}\tag{1}F=\frac{1}{4\pi\epsilon}\cdot\frac{q_1q_2}{r^2}\end{equation} $$ $4\pi r^2$ factor in the denominator expresses directly ...
26
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4answers
8k views

Why do same/opposite electric charges repel/attract each other, respectively?

I know plus pushes another plus away, but why, really, do they do that? On the other hand, molecules of the same type are attracted to each other. I find that weird. I do know some stuff about four ...
2
votes
2answers
187 views

My conundrum with Gauss’ law in electrostatics

If I use Gauss’ law to calculate the electric field outside of a charged (conducting or insulating) sphere or a point charge, the fields are the same. However, as a test approaches a point charge, the ...
2
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1answer
229 views

Coulomb interaction as virtual particles exchange?

I've been reading about virtual particle exchanges in physics books and in Physics SA posts, where a particle interpretation of gravity and Coulomb interaction is established. The Feynman Diagram ...
9
votes
3answers
471 views

How would charge be distributed in charged conductors if the Coulomb law was not ${1}/{r^2}$?

Would the excess charge on a conductor move to surface until the electric field inside become zero if the Coulomb law was for example $\frac{1}{r^3}$? If yes, would the distribution $\sigma(x,y)$ be ...
1
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0answers
33 views

How to derive the classical Hartree potential for a slab system?

I am now working on a slab system, but encountered some problems on the classical Hartree potential. This slab system is infinity along x-y plane, and has finite size along $z$ axis $z\in[0,L]$. I ...
1
vote
1answer
164 views

Coulomb force on the center of a hexagon?

Six point charges $q$ are at the corners of a regular hexagon that has sides of length $a$. What is the force on another charge $Q$ which is located in the center of the hexagon? What is the force on ...
3
votes
1answer
228 views

Information content of the electrostatic Maxwell equations vs Coulomb's Law vs Poisson's Equation

In electrostatics, we have Maxwell's equations: $\nabla \cdot E = \rho$ $\nabla \times E = 0$ These four equations (the second line standing for three equations) can also be written in terms of the ...
7
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1answer
145 views

Does QED provide a closed form for Coulomb logarithms?

The classical models for the integrand as well as the cut-offs in computing the Coulomb logarithm are pretty rough. Does quantum electrodynamics have definite expressions for the quantity ...
1
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0answers
83 views

Understanding unit vectors

Trying to understand how the unit vector ${\mathcal{\hat{r}}}$ defined as $\frac{r' - r}{|r' - r|} $ (where $r'$ is the source point) works in this problem: Work out the electric field, $E$, at point ...
4
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2answers
297 views

When studying electrodynamics do we assume Maxwell's Equations or derive them?

This question is because something made me confused. I always thought that the idea behind electrodynamics was to postulate some things, like Coulomb's law in electrostatics and so on, and then ...
1
vote
1answer
218 views

Maximum electric field in a circle

I have a question as follows: "Show that $E_x $ on the axis of a ring charge of radius $a$ has its maximum value at $x = \pm a /\sqrt{2} $. Sketch $E_x$ versus x for both positivve and negative ...
9
votes
7answers
1k views

Why is there a factor of $4\pi$ in certain force equations?

I mean to ask why there is $4\pi$ present in force equations governing electricity? Though all objects in universe are not spherical and circular, the constant of proportionality in both equations ...
0
votes
1answer
149 views

Do we need infinite energy to make 2 similar charges touch only in theory?

By Coulomb's law, say if we have 2 point particles each having a charge of +1C then by the formula, F = k/(d)^2 if we need to make the distance between them zero, clearly y the formula, we need to ...
0
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3answers
265 views

Generalized Coulomb's Law

This question is about the generalization of Coulomb's law to continuous bodies of charge. The basic statement of Coulomb's Law involves two discrete charges $q_1$ an $q_2$: $$\vec{F}_i = \frac{1}{4 ...
0
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2answers
331 views

Why do we say that in Coulomb's law the force is proportional to $\frac{1}{r^{2}}$ and not $\frac{1}{r^{3}}$?

I am going over Coulomb's law and there is something that is a bit confusing for me: According to Coulomb's law, if I have a charge $q_{1}$ at a point $\vec{r_{1}}$ and a charge $q_{2}$ at a point ...
2
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4answers
3k views

The relation between Gauss's law and Coulomb law and why is it important that the electric field decrease proportionally to $\frac{1}{r^{2}}$?

My question relates to the third MIT's video lecture about Electricity and Magnetism, specifically from $21:18-22:00$ : http://youtu.be/XaaP1bWFjDA?t=21m18s I have watched the development of Gauss's ...
6
votes
2answers
547 views

How does one show using QED that same/opposite electric charges repel/attract each other, respectively?

Why do same charges repel each other and opposite charges attract each other (please explain the phenomenon using real laws of nature (QED) not with the approximation model)?
3
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1answer
232 views

Coulomb potential

It is known that the Coulomb potential can be obtained by Fourier transform of the propagator from E&M. Is this because one of Maxwell's equations have the form $\nabla \cdot \mathbf{E}=\rho$?
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2answers
855 views

Is Newton's universal gravitational constant the inverse of permittivity of mass in vacuum?

Is it possible to consider Newton's universal gravitational constant, $G$, as inverse of vacuum permittivity of mass? $$\epsilon_m=\frac {1}{4\pi G}$$ if so, then vacuum permeability of mass will ...