Coulomb's Law Calculator – F = kq₁q₂/r²

Calculate electrostatic force between two charges using Coulomb's Law F = kq₁q₂/r².

Charge q₁ (C)

Charge q₂ (C)

Distance r (m)

How It Works

Enter charge 1 (q₁) and charge 2 (q₂) in Coulombs, and the distance r in meters. The Coulomb constant k = 8.9875 × 10⁹ N·m²/C² is used automatically.

Formula

F = k × q₁ × q₂ ÷ r²

Frequently Asked Questions

What is Coulomb's constant?

k ≈ 8.9875 × 10⁹ N·m²/C². It relates force to charge magnitudes and distance in Coulomb's law.

When is the force attractive vs repulsive?

Like charges (same sign) repel; opposite charges attract. The sign of the product q₁×q₂ determines this.