# PHYS 2212 Module 1.3

## Coulomb’s Law

1.3 Coulomb’s Law

### Learning Objectives

By the end of this section, you will be able to:

• Describe the electric force, both qualitatively and quantitatively
• Calculate the force that charges exert on each other
• Determine the direction of the electric force for different source charges
• Correctly describe and apply the superposition principle for multiple source charges

### Coulomb’s Law

The magnitude of the electric force (or Coulomb force) between two electrically charged particles is equal to

If the charges have the same sign, the force is in the same direction as r showing a repelling force. If the charges have different signs, the force is in the opposite direction of r showing an attracting force.

Discuss!

Reflect on this question and take notes on how you would answer it. Then we will share these thoughts together in a class discussion.

Compare the magnitudes of the gravitational and electric forces exerted by the nucleus of a hydrogen atom on an electron when the two are 0.050 nm apart.

Practice!