Coulomb's Law Calculator
Calculate the electrostatic force between two charges using Coulomb's law: F = kq₁q₂/r².
Enter charges and distance.
Coulomb's Law
F = k × |q₁ × q₂| / r²
k = 8.9875 × 10⁹ N·m²/C²
k = 8.9875 × 10⁹ N·m²/C²
Example: q₁ = 1 μC, q₂ = 2 μC, r = 5 cm
F = 8.99×10⁹ × (1×10⁻⁶)(2×10⁻⁶) / (0.05)² = 7.19 N
F = 8.99×10⁹ × (1×10⁻⁶)(2×10⁻⁶) / (0.05)² = 7.19 N
FAQ
Is the force attractive or repulsive?
Like charges (both + or both −) repel. Unlike charges (one + and one −) attract. The magnitude formula is the same either way.
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Last updated: 2026-08-08