03 // Bidirectional STEM Calculators // PHYSICSF = (k_e × q₁ × q₂) / r²

Coulomb's Law Electrostatic Force Calculator

Coulomb's Law calculates the electrostatic attraction or repulsion force F between two point charges q₁ and q₂ separated by distance r in free space using Coulomb's constant k_e = 8.98755 × 10⁹ N·m²/C².

F = (k_e × q₁ × q₂) / r²

Pick which value you want to calculate (or type into any field):Solving for: F — Electrostatic Force

Electrostatic ForceCalculated

Magnitude of force between charges in Newtons

1.0000e-61,000,000.00

Point Charge 1

First charge magnitude in microcoulombs (10⁻⁶ C)

0.0110,000.00

unit

Point Charge 2

Second charge magnitude in microcoulombs (10⁻⁶ C)

0.0110,000.00

unit

Charge Separation

Distance between point charges in meters

0.001100

Calculated Result · Electrostatic Force (F)

8.9875N

Converted units:

Step-by-Step Calculation

01Canonical Law: F = (k_e × q₁ × q₂) / r²

02Given Inputs (Base Units): q₁ (μC) = 10, q₂ (μC) = 10, r = 0.3162 m

03Solve for F (Electrostatic Force): F = 8.9875 N

Real-World Reference Values

Coulomb Constant (k_e = 1/4πε₀)8.98755 × 10⁹ N·m²/C²

Vacuum permittivity ε₀ = 8.854 × 10⁻¹² F/m

Elementary Charge (e)1.60218 × 10⁻¹⁹ C

Single proton or electron charge quantum

Two 10 μC Charges @ 10 cmF = 89.88 N (20.2 lbf)

Strong macroscopic force from microcoulomb static charge

20-Row Comparison Table

Electrostatic Force (F) · Point Charge 1 (q₁ (μC))

Compare across:

Coulomb's Law Electrostatic Force Calculator — Point Charge 1 → Electrostatic Force
#	Point Charge 1 (q₁ (μC))	Electrostatic Force (N)	Δ %
01	10 Current	8.9875 N	0.00%
02	72.9041	65.5229 N	+629.04%
03	145.7983	131.0368 N	+1357.98%
04	218.6924	196.5506 N	+2086.92%
05	291.5866	262.0645 N	+2815.87%
06	364.4807	327.5784 N	+3544.81%
07	437.3748	393.0923 N	+4273.75%
08	510.269	458.6062 N	+5002.69%
09	583.1631	524.1201 N	+5731.63%
10	656.0572	589.634 N	+6460.57%
11	728.9514	655.1479 N	+7189.51%
12	801.8455	720.6617 N	+7918.46%
13	874.7397	786.1756 N	+8647.40%
14	947.6338	851.6895 N	+9376.34%
15	1,020.53	917.2034 N	+10105.28%
16	1,093.42	982.7173 N	+10834.22%
17	1,166.32	1,048.23 N	+11563.16%
18	1,239.21	1,113.75 N	+12292.10%
19	1,312.10	1,179.26 N	+13021.04%
20	1,385.00	1,244.77 N	+13749.99%

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Frequently Asked Questions

Why are charges q₁ and q₂ entered in microcoulombs (μC)?+

One full Coulomb of isolated static charge is enormous (two 1 C charges 1 meter apart exert 9 billion Newtons of force); practical lab charges are measured in μC or nC.

How do I know if the force is attractive or repulsive?+

Like charges (+/+ or -/-) repel, while opposite charges (+/-) attract along the line joining their centers.

How does a dielectric medium modify Coulomb's Law?+

Immersion in a dielectric medium with relative permittivity ε_r divides the electrostatic force by ε_r (e.g., ε_r ≈ 80 in pure water).