Coulomb's Law Calculator
Calculate electrostatic force between charged particles using Coulomb's law
Calculate Electrostatic Force
Select which parameter you want to calculate. The other three will be used as inputs.
Magnitude of the first electric charge
Magnitude of the second electric charge
Shortest distance between the centers of the charges
Calculation Results
Formula used: F = kₑ × q₁ × q₂ / r²
Where: F = force (N), kₑ = Coulomb's constant, q₁,q₂ = charges (C), r = distance (m)
Example Calculations
Hydrogen Atom (Proton and Electron)
Proton charge: +1.602 × 10⁻¹⁹ C
Electron charge: -1.602 × 10⁻¹⁹ C
Distance: ~5.29 × 10⁻¹¹ m (Bohr radius)
Force: 8.24 × 10⁻⁸ N (attractive)
Two Like Charges
Charge 1: +10 nC
Charge 2: +5 nC
Distance: 1 cm = 0.01 m
Force: 4.49 × 10⁻⁴ N (repulsive)
Force Types
Repulsive Force
Like charges (+ and + or - and -)
Charges push away from each other
Attractive Force
Opposite charges (+ and -)
Charges pull toward each other
Important Constants
Coulomb's Constant (kₑ)
8.9875 × 10⁹ N⋅m²/C²
Elementary Charge (e)
1.602 × 10⁻¹⁹ C
Permittivity (ε₀)
8.854 × 10⁻¹² F/m
Understanding Coulomb's Law
What is Coulomb's Law?
Coulomb's law describes the electrostatic force between electrically charged particles. It states that the force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.
Key Principles
- •Inverse Square Law: Force decreases with distance squared
- •Point Charges: Applies to charges concentrated at points
- •Superposition: Forces from multiple charges add vectorially
Mathematical Formula
F = kₑ × (q₁ × q₂) / r²
F: Electrostatic force (Newtons)
kₑ: Coulomb's constant (8.988 × 10⁹ N⋅m²/C²)
q₁, q₂: Electric charges (Coulombs)
r: Distance between charges (meters)
Conditions for Validity
- •Charges must be stationary (electrostatics)
- •Point charges or spherically symmetric distributions
- •Charges cannot overlap (r > 0)