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Physics

Coulomb’s Law Calculator

F = kq₁q₂/r². Free online Coulomb’s Law Calculator. Calculate coulomb’s law online — fast, accurate, mobile-friendly, no signup needed.

Force (N)
0.899

Derivation

  1. ├── 01Givenq1 = 1.0000e-6, q2 = 1.0000e-6, r = 0.1
  2. ├── 02Formula899e7 × t × a / (n²)
  3. └── 03Compute Force (N)0.899
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§01What is

Understanding the Coulomb’s Law Calculator

The Coulomb’s Law Calculator computes Force (N) from 3 inputs: q₁ (c), q₂ (c), distance (m). F = kq₁q₂/r².

Physics is the toolkit for turning a real-world observation into a prediction. Whether it’s a falling object, a moving car, or a stressed beam, the equations here are the same ones every engineer relies on. The Coulomb’s Law Calculator sits in that toolkit — it F = kq₁q₂/r². Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

899e7 × t × a / (n²)

Where

q1
q₁ (C)
q2
q₂ (C)
r
Distance (m)
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: q₁ (C) = 0.000001, q₂ (C) = 0.000001, Distance (m) = 0.1.

  1. 01Start by noting the input — q₁ (C): 0.000001.
  2. 02Start by noting the input — q₂ (C): 0.000001.
  3. 03Start by noting the input — Distance (m): 0.1.
  4. 04Substitute these values into the formula: 899e7 × t × a / (n²)
  5. 05Compute Force (N): the calculator returns 0.899.
  6. 06Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04Variants

Common Coulomb’s Law Problems

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.

01 · PATTERN

q₁ (C) halved

q1 = 5.00000e-7 (from 1.00000e-6)

Keep every other input at its default and halve the q₁ (c). See how force (n) responds.

  1. 01New q₁ (C): 5.00000e-7
  2. 02Baseline Force (N): 0.899
  3. 03New Force (N): 0.4495
  4. 04Force (N) decreases by 50% → use this sensitivity to plan for real-world variation.
02 · PATTERN

q₁ (C) doubled

q1 = 2.00000e-6 (from 1.00000e-6)

Keep every other input at its default and double the q₁ (c). See how force (n) responds.

  1. 01New q₁ (C): 2.00000e-6
  2. 02Baseline Force (N): 0.899
  3. 03New Force (N): 1.798
  4. 04Force (N) increases by 100% → use this sensitivity to plan for real-world variation.
03 · PATTERN

q₂ (C) halved

q2 = 5.00000e-7 (from 1.00000e-6)

Keep every other input at its default and halve the q₂ (c). See how force (n) responds.

  1. 01New q₂ (C): 5.00000e-7
  2. 02Baseline Force (N): 0.899
  3. 03New Force (N): 0.4495
  4. 04Force (N) decreases by 50% → use this sensitivity to plan for real-world variation.
04 · PATTERN

q₂ (C) doubled

q2 = 2.00000e-6 (from 1.00000e-6)

Keep every other input at its default and double the q₂ (c). See how force (n) responds.

  1. 01New q₂ (C): 2.00000e-6
  2. 02Baseline Force (N): 0.899
  3. 03New Force (N): 1.798
  4. 04Force (N) increases by 100% → use this sensitivity to plan for real-world variation.
§05FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
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