Coulomb's law

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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.

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This is because electric charges make an electric field, such as magnetics make a magnetic field. When both electric charges make their own field, as two fields will exist in one space at the same time, and they will make force to each other. The force they make to each other is called Coulomb's force or Electrostatic force. Coulomb's law explains how big the force will be.

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F = {K_c}\frac{q_1q_2}{r^2}

Coulomb's law explains that the force scale F is relative to ratio of q_1,q_2,\frac{1}{r^2}.

q_1 and q_2 are the scales of each electric charge. r is the distance between the two electric charges. And K_c has a certain value. It does not change relative to q_1, q_2 or r. While {K_c} remains constant, when multiples of q_1 and q_2 become bigger, the electrostatic force will also get bigger. When the distance r become bigger, the electrostatic force will become smaller to ratio of \frac{1}{r^2}.
The exact size of K_c is 
k_c &= 8.987\ 551\ 787\ \times 10^9 \\
 \approx 9 \times 10^9N m2 C−2 (or m F−1). This constant is called Coulomb's Force Constant or Electrostatic Force Constant.

Inverse-square law[change | change source]

The relation between the force F and the distance r follows the Inverse-square Law. Inverse-square law means that when the distance r grows bigger, electrostatic force will become smaller by the ratio \frac{1}{r^2}. Gravitation, Electromagnetic radiation, Sound Intensity also follows this law.

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