Coulomb’s Law Force
Coulomb’s Law Force
Like charges repel and opposite charges attract with a force set by Coulomb’s law — the electrostatic analogue of gravitation.
The force is F = k_e·q_1·q_2/r². where k_e is Coulomb’s constant, q_1 and q_2 the charges and r their separation.
Inputs
k_e := 8.99e9 N·m^2/C^2=8.99e+09 kg·m^3/A^2/s^4
q_1 := 2e-6 C=2e-06 C
q_2 := 3e-6 C=3e-06 C
r := 0.05 m=50 mm
Apply Coulomb’s law.
F := k_e·q_1·q_2/r^2=21.58 N
Results
The inverse-square law makes the force fall off rapidly with distance. A positive result here is a repulsion between like charges.
Assumptions & limitations
- Point charges in vacuum/air.
- Static charges.
- Separation centre-to-centre.