Coulomb’s Law Calculator
Calculate electrostatic force between two point charges.
Formula
F = k|q1q2|/r².
What Does Coulomb’s Law Calculate?
Coulomb’s law estimates the magnitude of electrostatic force between two ideal point charges. Force grows with charge magnitude and falls rapidly as separation increases.
Example Calculation
Two charges of 1 μC each separated by 0.10 m produce a force of about 0.899 N.
Factors That Affect the Result
Charges must be entered in coulombs and distance in meters. Because distance is squared, doubling separation reduces force to one quarter. The calculator reports magnitude; the signs of charges determine whether the interaction is attractive or repulsive.
Interpreting the Result
Like charges repel and opposite charges attract. The point-charge model is most accurate when charge distributions are small relative to their separation.
Frequently Asked Questions
What value of k is used?
Approximately 8.98755 × 10⁹ N·m²/C².
Why is force always shown positive?
The tool reports force magnitude; direction must be inferred from charge signs.
Can I enter microcoulombs?
Convert μC to C by multiplying by 10⁻⁶.
Related Tools
Formula and Practical Limits
Coulomb’s law models the electrostatic force between ideal point charges. Force varies inversely with distance squared and depends on the surrounding medium; extended charge distributions may require a more detailed model.