Two identically charged balls are a certain distance apart.The vectors in the diagram below show the magnitude and direction of the electrostatic force on each ball. Suppose the charge on the left ball is now doubled (represented by two plus signs).Which diagram below best represents the forces that now act on the two balls?

Question

Two identically charged balls are a certain distance apart.The vectors in the diagram below show the magnitude and direction of the electrostatic force on each ball.  Suppose the charge on the left ball is now doubled (represented by two plus signs).Which diagram below best represents the forces that now act on the two balls?

Quizplus · Accepted Answer

According to Coulomb's Law, the electrostatic force between two charged objects is directly proportional to the product of their charges and inversely proportional to the square of the distance between them. 
If the charge on the left ball is doubled, the force between the two balls will increase by a factor of 2. The direction of the force on the left ball will remain the same but the direction of the force on the right ball will reverse. Diagram C shows the correct magnitude and direction of the forces on both balls after doubling the charge on the left ball.

Two Identically Charged Balls Are a Certain Distance Apart