Electric Field Mapper

Click on the dark area to drop a charge. The glowing lines show the electric field — the direction a tiny positive test charge would be pushed at every point. Field lines stream out of positive charges and into negative ones, and they never cross. Drag charges to reshape the field.

Click empty space to add a charge Drag a charge to move it; shift-click to remove Lines leave +, enter −, and never cross

Next charge

What you are seeing

Reading field lines

The direction of a line at any point is the direction of the force on a positive test charge there. Where lines are crowded together, the field is strong; where they spread out, it is weak. Lines start on positive charges and end on negative ones.

Try these

One charge alone: lines radiate straight out (or in). One + and one −: a dipole, with lines curving from the plus to the minus. Two of the same sign: lines push apart, with a bare patch between them where the field nearly cancels.