Coulomb's Law
Summary
- The force between two point charges is…
- directly proportional to the magnitude of each charge (q1, q2)
- inversely proportional to square of the separation between their centers (r)
- directed along the line connecting their centers (r)
- This relationship is known as Coulomb's law.
- As an equation it is usually written in one of two forms…
where…F = k q1q2 r2 F = magnitude of the electrostatic force ke = electrostatic constant = 8.99 × 109 N m2/C2 q1, q2 = charges of the two objects r = separation between the charges
where…F = 1 q1q2 r̂ 4πε0 r2 F = electrostatic force vector ε0 = vacuum permittivity = 8.8541878128 × 10−12 C2/N m2 q1, q2 = charges of the two objects r = separation between the charges r̂ = unit vector in the radial direction