# Questions tagged [coulombs-law]

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

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### On the collision of two electrons in a particle accelerator

The coulombic force between two charges is $$F = \frac{k q_{1} q_{2}}{r^{2}}$$ For two negative charges this will be repulsive. From the equation, as $r$ tends to zero the force approaches infinity....
1answer
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### What is the intuition behind why $\vec{E} = \int \mathrm{d}\vec{E}$ works for summing up infinitesimal contributions of electric field?

Say you want to find the electric field, $\vec{E}$, at some point in space, $P$, which is induced by some uniformly charged rod, $Q$, of known length, $L$. What you would do is break this charged rod ...
1answer
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### Ewald summations and series convergence

Does anyone have a explanation of why the direct summation of the coulomb interactions between the ions of a crystal structure which might be conditionally convergent is mathematically allowed to be ...
1answer
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### Where does Coulomb's constant, $k_e$, come from?

I'm familiar with Coulomb's law, $\vec{F} = k_e\frac{q_1q_2}{r^2}$, and know how to apply it (having used it extensively in practice, on exams, etc). I find that the $\frac{q_1q_2}{r^2}$ "part&...
1answer
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### Electric field computation with two point-charges and an infinite conducting sheet [closed]

Coordinates in this question are in metres: An infinitely large conducting metal sheet is located at z=0 (covers the xy plane). Point charge of 20 μC is at (0, 0, 1) and of -10 μC is at (2, 0, 1). ...
1answer
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### Coulomb's Law: Determining the magnitude and direction with three charges as given [closed]

It would be appreciated if someone can confirm if I am in a right path in solving this problem. The problem goes this way. Consider three charges on a coordinate system. Charge $q_1$ = +30 nC is at ...
1answer
48 views

### Net Coulomb Force on a charge in a system

Suppose that there are $n$ charges each at rest and positioned at the vertices of an $n$-sided regular polygon with side length $l$. Each charge has a magnitude of $q$ $C$. Can a general formula be ...
1answer
62 views

### Electric forces in dynamic conditions

The coulomb's law is limited to static charges. This made me think: Is it because the distance is not exactly defined when charges are moving so the dynamic condition isn't very much pertinent to ...
0answers
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### When do these two point charges meet? [duplicate]

Two point charges in the vacuum (so ignore all frictions). They have opposite signs so they will move towards each other under Coulomb's force. The magnitude of their charges are $q_1$ and $q_2$ ...
2answers
197 views

### What is the cause of electric force?

Electric force is observed during the interaction of two charged objects. What is exactly happening to make this force possible?. Previously, I assumed it may be due to the interaction of the two ...
1answer
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### Superposition Principle and Forces

Why does Griffiths write in his book - "For not only does the force on test charge $Q$ depend on the separation distance $r$ between the charges, it also depends on both their velocities and on ...
2answers
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### How is the Coulomb potential infinity resolved in quantum field theory?

People always says that the infinity of the coulomb potential $V(r)=\frac{k}{r}$ as $r$ approach to zero is resolved in quantum field theory. I would like to know how this is done.
1answer
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### How do two charged insulating spheres separated by a finite distance between their centres interact?

< I was solving problems of electrostatics from "Pathfinder for Olympiad and JEE Advanced Physics" by Arvind Tiwari and Sachin Singh when I encountered this problem. I can understand that the ...
2answers
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### Is equation $1/4πε_0$ in Coulombs law a scalar? Plus a question involving Jefimenko's equations [closed]

Is the equation of $1/4πε_0$ in Coulombs law a scalar? Also, does this equation equate to Coulombs constant? In addition, why does Jefimenko use $H=1/4π...$ in his equations? What is the significance ...
1answer
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### Fourier Transform of Coulomb potential in QFT

I am master student of particle physics and I want to find coulomb potential $V(r)$ from $\tilde{V}(p)$ in Schwartz-Quantum Field Theory and the Standard Model what I have as $\tilde{V}(p)$ from 16....
0answers
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### Why the force is inversly proportional to the square of distance? [duplicate]

Lesser the distance higher the force of attraction.but why it is the square of distance?And also the reason i guess for this force is the attraction force between atoms ( electrons of one atom and ...