Coulomb's Law Calculator

Coulomb's Law quantifies the amount of electrostatic force between two stationary, electrically charged particles. The fundamental mathematical expression is defined as F = k * (q1 * q2) / r^2, where F represents the electrostatic force, k is Coulomb's constant, q1 and q2 denote the magnitudes of the two point charges, and r signifies the straight-line distance between them. When charges are immersed in a medium other than a vacuum, the force is scaled down by the relative permittivity (or dielectric constant) of that specific material. Coulomb's constant itself is calculated as k = 1 / (4 * pi * epsilon_0), relying on the vacuum permittivity constant.

Imagine two point charges situated in a vacuum. Let the first charge be q1 = 3 microcoulombs (3 * 10^-6 C) and the second charge be q2 = -5 microcoulombs (-5 * 10^-6 C), separated by a distance of 0.5 meters. Using Coulomb's constant k approximately equal to 8.99 * 10^9 N*m^2/C^2, we apply the formula F = k * (q1 * q2) / r^2. Multiplying the charges gives (3 * 10^-6) * (-5 * 10^-6) = -1.5 * 10^-11 C^2. Squaring the distance yields 0.5^2 = 0.25 m^2. Dividing -1.5 * 10^-11 by 0.25 results in -6 * 10^-11. Finally, multiplying by Coulomb's constant yields an attractive force magnitude of approximately 0.539 Newtons, with the negative sign indicating mutual attraction.

Always convert your input values into standard SI units before calculating: use Coulombs (C) for charge instead of microcoulombs or nanocoulombs, and meters (m) for distance instead of centimeters or millimeters. Remember that relative permittivity for a vacuum or air is essentially 1, but dielectric materials like water or glass will significantly diminish the net electrostatic force between charges.