Peoples Physics Concepts

12.2 Coulomb’s Law

12.2 Coulomb’s Law

• Solve problems involving Coulomb’s Law.

Students will learn how to solve problems involving Coulomb’s Law.

Key Equations

F=

kq 1 q 2

r^2







k The electric constant,k= 8. 987 × 109 N·m^2 C−^2.

q 1 ,q 2 Magnitude of the charges, units of Coulombs (C)

r Distance between charges, m

Guidance

The Coulomb Force Law states that any two charged particles(q 1 ,q 2 )— with charge measured in units of
Coulombs — at a distancerfrom each other will experience a force of repulsion or attraction along the line joining
them equal to:

~Fe=kq^1 q^2

r^2

The Coulomb Force [1]

Where

k= 8. 987 × 109 N·m^2 ·C−^2 The Electric Constant

This looks a lot like the Law of Universal Gravitation, which deals with attraction between objects with mass. The

big difference is that while any two masses experience mutualattraction, two charges can either attract or repel

each other, depending on whether the signs of their charges are alike:

Like gravitational (and all other) forces, Coulomb forces add as vectors. Thus to find the force on a charge from an

arrangement of charges, one needs to find the vector sum of the force from each charge in the arrangement.