Opposite Charges Attract - Electric Fields & Electrostatics Step by Step

A positive charge and a negative charge pull toward each other. The force pair is still equal in size and opposite in direction.

Example

A positive charge and a negative charge pull toward each other. The force pair is still equal in size and opposite in direction. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

The signs are opposite

Put a positive 2 coulomb charge on the left and a negative 3 coulomb charge on the right.

q_{\text{left}} = +2\ \text{C}\qquad q_{\text{right}} = -3\ \text{C}

Opposite signs attract

Because the signs are opposite, each charge is pulled toward the other one. The left force points right, and the right force points left.

+ \text{ with } - \Rightarrow \text{attract}

The pair is still equal and opposite

Attraction changes the directions, not the pair rule. Each charge feels a force of 6 newtons, and the arrows point toward each other.

F_{\text{left}} = F_{\text{right}} = 6\ \text{N}

Attraction still uses matched sizes

The sign change flips the arrow directions, not the equality of the pair. The diagram draws the 6 newton row; the table shows that the size match is the rule.

\begin{array}{c|c}F_{\text{left}}&F_{\text{right}}\\4\ \text{N}&4\ \text{N}\\6\ \text{N}&6\ \text{N}\\8\ \text{N}&8\ \text{N}\\\end{array}

electrostatics Opposite charge signs make the force pair point toward the space between the charges.