Find the electrostatic force F = k q₁ q₂ / r² between two point charges.
| Force (N) | – |
Use this calculator for two point charges in vacuum (or air, to a good approximation). Coulomb’s constant is k ≈ 8.99×10⁹ N·m²/C². Same-sign charges give a positive F in this 1D product (they repel); opposite signs attract. r is the centre-to-centre separation.
Two 1 μC charges 10 cm apart give about 0.90 N. A microcoulomb (1e-6 C) is already a large laboratory charge. The formula is for point charges or spheres whose charge sits on the surface; it is not a field map of an extended distribution.
q₁ (C): First charge in coulombs. 1 μC is 1e-6 C.
q₂ (C): Second charge in coulombs.
Distance (m): Separation between the charges, in metres.
Force (N): Signed 1D force. Positive means same-sign (repulsion).
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