The three colored charges can be dragged to position them, and their charge values can be altered using the sliders.[br]The slider at right controls whether the charges represent point particles located in the plane, or infinitely long charged rods viewed end-on.[br]The E-field sensor displays the electric field vector at its location in the plane; drag the green point to sample the field elsewhere.[br][b]Drag the purple point to trace more field lines.[/b] Drawn lines will be retained until the charges are altered, or the view is adjusted or cleaned up.

[i]Java version features much faster field line plotting than HTML5 version.[/i]