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

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Deriving Coulomb's law from quantum electrodynamics [duplicate]

Is it possible to derive the Coulomb's law using the principles of quantum electrodynamics? How?
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where does the term half in the formula of electrostatic potential energy comes from?(system of point charges)

Electrostatic potential energy stored in a system of point charges (from wikipedia) The electrostatic potential energy $U_E$ stored in a system of N charges q1, q2, ..., qN at positions r1, r2, ...
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a question about work needed to move a charge towards another one [duplicate]

Consider two charges $q_1>0$ & $q_2>0$ separated by a distance $d_1$, and we want to move charge $q_2$ to a distance $d_2$ from $d_1$ where $d_1-d_2>0$. I need to calculate the work ...
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simple force question

So given this diagram, I was supposed to find the magnitude and direction of the net force on the -10nC charge on the bottom right corner. I found the magnitude by myself using Coulomb's law for the ...
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dipole field on axis twice the field on perpendicular bisector

Why is the dipole field on axis twice the field on perpendicular bisector? For the perpendicular bisector: Lets assume -q is right from of the origin and +q is left from the origin, both a distance a ...
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What is the intuitive meaning behind Coulomb's constant $k_e$?

What is the intuitive meaning behind Coulomb's constant $k_e$? If the force of an electric field can be calculated by $$F=k_eqQ/d^2$$ If I could guess I would say $k_e$ is the acceleration but I am ...
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192 views

How to find the electric field of a charged tube?

Let's say there is a charged tube(cylinder with no top or bottom) with radius $a$, length $l$ and charge $q$ and a point which is collinear with the centre of the charged tube. Anyway, since we can ...
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Will the electrostatic force between two charges change if we place a metal plate between them?

If a thin metal plate is placed between two charges $+q$ and $+q$, will this cause a change in the electrostatic force acting on one charge due to another? What is the concept behind this? What will ...
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Electron Beam Welding equation

I am studying for a nuclear physics course right now and came across a question and topic that sparked my interest - Electron Beam Welding. As I understand it, the process heats up the metal by ...
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188 views

Electric force between charges in two different media

As far as I know, Coulomb's law of electrostatic force is applicable on two different charges situated in same medium. But if two individual charges are in different media (say one charge on a iron ...
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21 views

Understanding the differences and applications of some electrical equations

In preparing for the AP Physics 2 test tomorrow, (the first year this test is being offered, so this material is not easily searchable), I've been doing some reviewing of the equation sheet and trying ...
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57 views

Graph of electric potential

In my AP physics guide the graph for electric potential (for a radial field, i.e. point charge) and gravitational potential (for radial field, i.e. point mass) slightly differ from each other and I ...
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Is there a fundamental relationship between Coulomb's law and Newton's Law of Gravitation? [duplicate]

It seems like the two equations are identical indicates that there is something more going on that unites them both, maybe in a cool way or something. Why are these two laws so similar?
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Gauss's Law of Electric Field how it actually works? & How Gauss derived it?

I want to know how Gauss derived his equation of Electric Field. Did he derive it from Coulomb's law? I don't think so. Please tell me some details about how this law works? inside a Gaussian ...
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62 views

Why do inverse square forces not rise asymptotically for $r\to 0$?

An example of an inverse square force is the gravitational force: $$ F = \dfrac{G m_1 m_2}{r^2}$$ For large bodies I can understand why the force does not rise asymptotically as you get closer. For ...
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Induction in Electrostatics

While solving some problems on electrostatics, I came across this question : Two balls carrying charges of +3 $\mu C$ and -3$\mu C$ attract each other with a force $F$. If a charge of +3$\mu C$ is ...
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Lower limit value of electric force [closed]

What is the lower limit value to the electric force between two charges separated by a fixed distance?
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Infinite force between two point charges as $r$ approaches 0 [duplicate]

According to coulombs law the Force experienced by two point charges increases with the inverse square of their separation. This would imply that at distances approaching 0, the Force approaches ...
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Force when distance between charge is zero

According to coulomb law $$ F = \frac{q_1q_2}{r^2} $$ I want to know what happens to force when $r=0$. If $F \to \infty$ then the charges can't be separated! But if an unlike charge of higher ...
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Special relativity, electromagnetic fields, charge and Q

Is it true, were Coulomb's constant k to be several orders of magnitude smaller, that there would be no (or increasingly negligible) magnetic fields generated by moving charges? The reason being the ...
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Direction of electric field lines and electrostatic force

Direction of electric field and electrostatic force should be same by the equation $$\vec{F} = \frac{k q q_0}{r^2}$$ Electric Field $$\vec{E} = \frac{k q}{r^2}$$ Let us suppose that there is a ...
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Why does the medium affect the Coulomb's constant but not the gravitational constant?

Why does the medium affect the Coulomb's constant but not the gravitational constant? My friend said maybe the particles of the medium affect the electric field. But the net charge in the medium is 0 ...
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How to calculate the force between line of charges?

As far as I know Coulomb's law only works for point charges but what if there are not any point charges? For example, let's imagine there are three rectangles with different sizes. First one is 50 cm, ...
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Isn't the Coulomb interaction a photon interaction between two charges?

Isn't the Coulomb interaction a photon interaction between two charges? if yes then what does the following text mean? (Many-particle Physics by Gerald D. Mahan.)
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Does the electric force on a charged particle in a uniform electric field increase?

If I have a proton in a uniform field between two parallel oppositely charged plates and the proton accelerates, the electric force acting on it stays constant seeing it is a uniform field and as a ...
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117 views

Origin of the Lorentz force from the point view of relativity?

I'm a physicist, when I'm working on the quantum spin hall effect, I recollected the high-school knowledge on Lorentz force and try to explain the origin of it, but didn't get it in the first glance. ...
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Why is the voltage of a battery equal to the emf?

We know that there is an electric field inside the battery that works against the moving electrons of a circuit. But there is also the chemical force of the battery that at some point become equal. ...
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Gauss Law for a Modified Coulomb's Law

A problem out of a certain popular book on electricity and magnetism dealt with the resulting electrostatic theory if Coulomb's law was replaced with the following equation: $$ \mathbf{F} = ...
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365 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 ...
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How did special relativity change physicists views on the two prominent inverse square laws (ie Newton grav and Coulomb's law)?

On page 107 in Hartle's Gravity -- An introduction to Einstein's General Relativity, he says the following With the success of special relativity it became apparent that the Newtonian theory of ...
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Coulomb's law and Gauss' Law

Which of these laws is more fundamental or forms the basis of electrostatics? I started off with Coulomb's law and then I studied Gauss' law. I was wondering which one is more universal? My professor ...
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60 views

How do photons mediate (or create) a force?

Is there a somewhat intuitive explanation as to why the exchange of a photon between two particles causes a force between those particles? Is there a difference in the way massless and massive ...
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32 views

What's the Relation between Potential of mechanics and electricity?

As we know that for a conservative force field, there is associated a Potential with the force. But we know there is a potential in electricity (That's voltage). My question is that is there any ...
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Is it equivalent to derive Gauss's law from discrete and continuous source distributions?

I've seen two derivations for Gauss's law in electrostatics. The first assumes a discrete charge distribution, the second a continuous one: Use superposition $$\vec{E}=\sum_{i=1}^n\vec{E}_i,$$ so ...
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How can I split a resultant force into its $x$ and $y$ components?

Point charge 3.5μC is located at x = 0, y = 0.30 m, point charge -3.5μC is located at x = 0 y = -0.30 m. What are (a)the magnitude and (b)direction of the total electric force that these charges ...
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My electrophorus doesn't work

I have failed in generating charge using electrophorus. The charging material was a balloon rubbed with hair until it became very full of static, as well as a small piece of Styrofoam rubbed with the ...
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225 views

Rigorous proof of Gauss' law for an arbitrary charge distribution from Coulomb's law

Most of the books about electromagnetism prove Gauss' law for a point charge in vacuum: $$ \Phi = \int_{\Sigma} \mathbf{E} \centerdot d \mathbf{S} = q/\epsilon_0 $$ and then simply state that for ...
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Repulsive force between same charged plates?

I understand that the attraction force between parallel plates of capacitor is the derivative of stored energy with respect to distance of the plates. But how could we find the repulsive force between ...
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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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Galilean and Lorentz Covariance in Julian Schwinger's book Electrodynamics

In the book Electrodynamics (pp. 8-11) Julian Schwinger "derives" (in this special case) the complete Maxwell equations from the Coulomb potential using only the Galilean transformation $$ ...
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Why is the current in an electric circuit constant?

Considering electrostatics, suppose we have two charges of equal value and opposite sign and we put electrons along the road between them: We know that the electrical force or field is different from ...
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657 views

Coulomb's Law in the presence of a strong gravitational field

I was under the impression that the $1/r^2$ falloff of various forces were because of the way the area of a expanding sphere scales. But that strict $1/r^2$ falloff would only be globally true in a ...
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A query regarding constant $\frac{1}{4\pi \epsilon_{0}}$ in Coulomb's Law [duplicate]

In our physics class we were discussing about Coulomb's Law and equation for the electrostatic force between two points: $$F_{e}=\frac{Q_{1}Q_{2}}{4\pi \epsilon_0 r^2}$$ From the equation a query ...
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If the field concept was invented by Faraday, then how did Newton interpret the $g$?

This is Newton's law of universal gravitation. $F=G\frac{m_1.m_2}{r^2}$ Gravitational field $g$ is derived from this formula $g=G\frac{m_1}{r^2}$ This is named gravitational "field" strength. If ...
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What are some most advanced theories explaining why same charge repel, opposite charge attract? [duplicate]

It is the holidays with a lot to think about. One of the thing that I couldn't get out of my mind was something I read in Stephen Hawking's "Brief History of Time". In it, he described the repelling ...
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Why according to Hund's first rule all electron with same spin should occupy orbitals when partially filling?

I get that because of coulomb repulsion initially all the electrons will not occupy the same site but will single occupy the orbitals.But while doing so how do they know to keep their spins aligned ...
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Is my representation of $\varphi$ Work function correct?

I am a middle-school so my understanding of physics may not be as solid as you professional physicists but never the less thought its worth a try to learn more. I read about photo-electric effect by ...
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542 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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Forces on moving charges

I want to know what are the total forces on a moving charge due to another charge. I heard that moving charges is the cause of all magnetism.So what I think is that if we have a charge in motion ...
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79 views

How does the force between two charges becomes zero?

In case of Coulombs law, $$ F=k\frac{q_1q_2}{d^2} $$ So, if $F=0$, then $q_1q_2$ must be 0. Is this true?