Coulomb's Law

Coulomb's Law

Every charged particle exerts a force on every other. Charles-Augustin de Coulomb measured this in 1785:

F = rac{k q_1 q_2}{r^2}

• k = $8.99 imes 10^9 ext{ N·m}^2/ ext{C}^2$ — Coulomb's constant
• q₁, q₂ — charges in Coulombs (positive or negative)
• r — distance between charges (m)
• F — force in Newtons (positive = repulsive, negative = attractive)

The Inverse-Square Law

Coulomb's law has the same $r^2$ dependence as Newton's gravity — both are long-range forces that never reach zero. The crucial difference: gravity is always attractive, while electric force can attract or repel.

Examples (q₁ = q₂ = 1 μC)

Your Task

Implement coulomb_force(q1, q2, r) returning the force in Newtons ($k = 8.99 imes 10^9$).