Coulomb's Law Calculator
Find the force of attraction or repulsion between two charges.
Your numbers
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Force magnitude (N)
Force magnitude (N)
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Nature of the force
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Coulomb's Law Calculator by TheCalcTools
How the Coulomb's Law Calculator works
Enter both charges in microcoulombs (use a negative sign for negative charges) and the distance between them.
The force is proportional to the product of the charges.
It falls with the square of the distance.
The formula
F = k |q₁ q₂| ÷ r²k = 8.9875517923 × 10⁹ N·m²/C²
Worked example
Using the default values shown in the calculator:
| Charge 1 (µC) | 5 |
|---|---|
| Charge 2 (µC) | -3 |
| Distance (m) | 0.2 |
- F = 8.99 × 10⁹ × 5 × 10⁻⁶ × 3 × 10⁻⁶ ÷ 0.2² = 3.370 N.
- The force is Attractive.
Result:
| Force magnitude (N) | 3.3703 |
|---|---|
| Nature of the force | Attractive |
Frequently asked questions
Do opposite charges attract?
Yes. Opposite charges attract and like charges repel.
How is it like gravity?
Both follow an inverse-square law, but the electric force is vastly stronger and can be repulsive.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.