Coulomb's law

Coulomb’s law allows us to explain the magnitude and sign of the electrostatic force between any two charged particles.

If two charged particles of charge q1 and q2 are separated by a distance d, then the force F between them is

$ F={{k q_1 q_2}\over{d^2}} $

where q1 and q2 are the charge of the two particles (in Coulombs), and k is the Coulomb constant – for charged particles in air, the value of the Coulomb constant is 8.988 × 109 N m2 C-2.

The direction of the force is attractive between opposite charges and repulsive between like charges and directed radially between the particles.

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