| Electromagnetism |
| --- |
|  |
| Electricity **·** Magnetism **·** Magnetic permeability |
| Electrostatics
Electric charge • Coulomb's law • Electric field • Electric flux • Gauss's law • Electric potential energy • Electric potential • Electrostatic induction • Electric dipole moment • Polarization density |
| Magnetostatics
Ampère's law • Electric current • Magnetic field • Magnetization • Magnetic flux • Biot–Savart law • Magnetic dipole moment • Gauss's law for magnetism |
| Electrodynamics
Lorentz force law • emf • Electromagnetic induction • Faraday’s law • Lenz's law • Displacement current • Maxwell's equations • EM field • Electromagnetic radiation • Liénard–Wiechert potential • Maxwell tensor • Eddy current |
| Electrical Network
Electrical conduction • Electrical resistance • Capacitance • Inductance • Impedance • Resonant cavities • Waveguides |
| Covariant formulation
Electromagnetic tensor • EM Stress-energy tensor • Four-current • Electromagnetic four-potential |
| * v
* t
* e
 |

Charles Augustin de Coulomb
**Coulomb's law** is a function developed in the 1780s by physicist Charles-Augustin de Coulomb. It explains how strong the force will be between two electrostatic charges. Electrostatic means electric charges without any motion.

Direction
---------

This picture shows how Coulomb's Force act; similar charges pushing against each other and opposite charges attract each other
Let's think of two electric charges existing in an empty space. If the two charges are opposite, (+) and (-) charges for example, they will attract each other. And if two charges are both the same, both (+) or both (-) for example, they will push each other. This is similar to how magnets act, as N and S attract each other, and as N and N, S and S push each other.

This is because electric charges make an electric field. If two fields exist in the same space at the same time, then the two fields exert (~ put) force on each other. The force they make on each other is called 'Coulomb's force' or the **electrostatic force**. Coulomb's law explains how big the force will be.

Scale
-----

Coulomb's law explains the scale between two electric charges.
The scale of electrostatic force follows the function below.

{\displaystyle F={K\_{c}}{\frac {q\_{1}q\_{2}}{r^{2}}}}
Coulomb's law explains that the force scale F is relative to ratio of {\displaystyle q\_{1},q\_{2}},{\displaystyle {\frac {1}{r^{2}}}}.

{\displaystyle q\_{1}} and {\displaystyle q\_{2}} are the scales of each electric charge. r is the distance between the two electric charges. And {\displaystyle K\_{c}} has a certain value. It does not change relative to {\displaystyle q\_{1}}, {\displaystyle q\_{2}} or r. While {\displaystyle {K\_{c}}} remains constant, when multiples of {\displaystyle q\_{1}} and {\displaystyle q\_{2}} become bigger, the **electrostatic force** will also get bigger. When the distance r becomes bigger, the electrostatic force will become smaller by the ratio of {\displaystyle {\frac {1}{r^{2}}}}.  

The exact size of {\displaystyle K\_{c}} is
{\displaystyle {\begin{aligned}k\_{c}&=8.987\ 551\ 787\ \times 10^{9}\\\end{aligned}}}
{\displaystyle \approx 9\times 10^{9}}N m2 C−2 (or m F−1). This constant is called **Coulomb's force constant** or the electrostatic force constant.

Inverse-square law
------------------

The relation between the force of pushing or pulling (F) and the distance between the particles (r) follows the Inverse-square Law. Inverse-square law means that when the distance r grows bigger, the force gets weaker by the ratio {\displaystyle {\frac {1}{r^{2}}}}. Gravitation, Electromagnetic radiation, and sound loudness also follow this law.

Related pages
-------------

* Coulomb, the SI unit of electric charge named after Charles-Augustin de Coulomb
* Inverse-square law, the physical law that shows the relation between distance and Intensity.
* Electrostatic
* Magnetic

Other websites
--------------

* *Coulomb's Law* on Project PHYSNET.
* A maze game for teaching Coulomb's Law Archived 2009-05-05 at the Wayback Machine

|  |  |
| --- | --- |
| Authority control: National Edit this at Wikidata | 
* Germany

 |