A fundamental and empirical law quantifying the electrostatic force between two charges.
Questions tagged [coulombs-law]
969 questions
128
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Can Maxwell's equations be derived from Coulomb's Law and Special Relativity?
As an exercise I sat down and derived the magnetic field produced by moving charges for a few contrived situations. I started out with Coulomb's Law and Special Relativity. For example, I derived the magnetic field produced by a current $I$ in an…
user1247
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votes
5 answers
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 universal forces. But why in general the general…
Muhammad Umer
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91
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3 answers
How does this baby rattle work?
Here's a gif showing how the balls move when I move the rattle. The circular tube hangs vertically, with the balls on the bottom. There are more images in the bottom.
The balls roll freely inside the tube
The inner diameter of the tube is larger…
Stewie Griffin
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83
votes
7 answers
Does Coulomb's Law, with Gauss's Law, imply the existence of only three spatial dimensions?
Coulomb's Law states that the fall-off of the strength of the electrostatic force is inversely proportional to the distance squared of the charges.
Gauss's law implies that the total flux through a surface completely enclosing a charge is…
Justin L.
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67
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7 answers
Fourier transform of the Coulomb potential
When trying to find the Fourier transform of the Coulomb potential
$$V(\mathbf{r})=-\frac{e^2}{r}$$
one is faced with the problem that the resulting integral is divergent. Usually, it is then argued to introduce a screening factor $e^{-\mu r}$ and…
Emerson
- 1,377
44
votes
6 answers
Why are so many forces explainable using inverse squares when space is three dimensional?
It seems paradoxical that the strength of so many phenomena (Newtonian gravity, Coulomb force) are calculable by the inverse square of distance.
However, since volume is determined by three dimensions and presumably these phenomena have to travel…
RD Ward
- 554
42
votes
3 answers
Deriving the Coulomb force equation from the idea of virtual photon exchange?
Since Newton's law of gravitation can be gotten out of Einstein's field equations as an approximation, I was wondering whether the same applies for the electromagnetic force being the exchange of virtual photons. Is there an equation governing the…
Meep
- 4,167
31
votes
5 answers
Why are atoms electrically neutral?
I get the grade-school explanation that "the number of electrons equals the number of protons", but the electric field drops off with distance. If the protons are concentrated in the nucleus and the electrons are nebulously around the atom in…
29
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2 answers
Basis for the Generalization of Physics to a Different Number of Dimensions
I am reading this really interesting book by Zwiebach called "A First Course in String Theory". Therein, he generalizes the laws of electrodynamics to the cases where dimensions are not 3+1. It's an intriguing idea but the way he generalizes seems…
user87745
23
votes
3 answers
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 $ϵ_0$ embedded in the electric field expression…
Jesus
- 655
22
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1 answer
How can supercapacitors not implode?
How can supercapacitors store $5\,\mathrm{coloumbs}$ and not implode due to the enormous force between the plates ($10^{15}\,\mathrm{N}$ if the plates are $1\,\mathrm{cm}$ apart)?
moonblink
- 1,159
22
votes
6 answers
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 is not enough. Which experiments did result to…
MOON
- 947
21
votes
7 answers
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 contain $4\pi$. Why?
Chaitanya
- 487
21
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2 answers
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 be:
$$\mu_m=\frac {1}{\epsilon_m c^2}$$
then…
user26425
20
votes
2 answers
Using photons to explain electrostatic force
I am trying to understand the idea of a force carrier with the following example.
Let's say there are two charges $A$ and $B$ that are a fixed distance from each other. What is causing the force on $B$ by $A$?
Classically charge $A$ has an…
cspirou
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