Electric force depends on charge and distance {Coulomb's law} {Coulomb law}. Electric force F between two charges varies directly with charge q and varies inversely with square of distance r between charges: F = k * q1 * q2 / r^2 = (1 / (4 * pi * e)) * q1 * q2 / r^2.
permittivity
Electric-force constant k depends on medium electric permittivity e: k = 1 / (4 * pi * e).
distance
Force varies with distance squared, because space is isotropic in all directions, time has no effect, and field-line number stays constant as surface area increases. Sphere surface area = 4 * pi * r^2.
charge
Force depends on both charges, because force is interaction. Electric force depends on charge linearly, because charge directly causes force. Because charges can be positive or negative, electric force can be attractive positive or repulsive negative. If both charges are positive or negative, electric force is positive. If one charge is positive and one charge is negative, electric force is negative.
comparison
Electric force is very strong compared to gravity. Gravitational force and electric force equations are similar, because interactions cause both forces and both forces radiate in all directions.
voltage
dW = F * ds = q * dV. F = q * dV / ds = q * E.
Physical Sciences>Physics>Electromagnetism>Force
5-Physics-Electromagnetism-Force
Outline of Knowledge Database Home Page
Description of Outline of Knowledge Database
Date Modified: 2022.0224