Coulomb’s Law

Learning Goals

Coulomb’s Law

Coulomb’s law describes the vector magnitude (which is always positive) of the electric force between two point charges:

where the constant k is given by k = 8.9875 x 10⁹ Nm²/C²

Items 2 and 3 above along with Coulomb’s law can be used to construct a vector diagram of any number of electric forces acting on a given charge.

Example

Five unknown charges are shown on the screen along with vectors representing the forces on each charge. You can click-drag on any charge to change its position.

Question: How many charges have like signs? What would the total charge be?

Move the charges around with your mouse. Try grouping them according to like sign. Pay particular attention to the forces as you move them around.

When you think you know the answer, click to see if you were right.