Coulomb's Law

on . Posted in Electrical Engineering

ohms pie chart 1electric force 2Coulomb's law is the magnitude of the electrostatic force between two electric charges.  In case of more than two electric charges, the superposition principle in addition to coulomb’s law is applied to calculate the net electronic force acting on any one charge. 

Coulomb's Law Index

According to this superposition principle, the total force acting on a given charge is equal to the vector sum of forces exerted on it by all the other charges.  The force between two charges can be attractive if the charges have opposite signs (one positive and one negative), or repulsive if the charges have the same sign (both positive or both negative).  The force follows an inverse square law, meaning that doubling the distance between charges reduces the force by a factor of four, while halving the distance increases the force by a factor of four.

Coulomb's law is fundamental to the understanding of electric forces and plays a crucial role in various fields, including electromagnetism, electrical engineering, and physics.  It provides a mathematica description of the force between charged particles and enables the calculation of electric forces and interactions in different systems.


Coulomb's Law formula

\( F_e \;=\; k_e \; ( q_1 \; q_2 \;/\; l^2 ) \)     (Coulomb's Law)

\( k_e \;=\;   F_e \; l^2 \;/\; q_1 \; q_2 \)

\( q_1 \;=\;   F_e \; l^2 \;/\; k_e \; q_2 \)

\( q_2 \;=\;   F_e \; l^2 \;/\; k_e \; q_1 \)

\( l \;=\; \sqrt{  k_e \; q_1 \; q_2 \;/\; F_e }  \)

Symbol English Metric
\( F_e \) = electrostatic force \(lbf\) \(N\)
\( k_e \) = Coulomb's constant (see physics constants) \(constant\)
\( q_1 \) = electric charge \(C\) \(C\)
\( q_2 \) = electric charge \(C\) \(C\)
\( l \) = distance between the two charges \(ft\) \(m\)


Coulomb's First Law

Two charged particles of same charge (positive or negative) will repel each other and two charged particles of opposite charges (one positive and one negative) will attract each other.

Coulomb's Second Law

The force of attraction or repulsion between the two electrically charged particles is directly proportional to the product of magnitudes of two charges and inversely proportional to the square of the distance between two charges.

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