Electric Field Lines Due to a Collection of Point Charges
This Demonstration shows the electric field lines and associated contours of the electric potential due to a collection of movable point charges. You can add or remove charges and vary the magnitude of each charge.
In this Demonstration, Mathematica calculates the field lines (black with arrows) and a set of equipotentials (gray) for a set of charges, represented by the gray locators. You can drag the charges. You can add or remove charges by holding down the Alt key (or the command key on a Mac) while clicking on either an empty space or an existing charge, respectively. Each charge is labeled with a number in red; you can vary the magnitude of the charge with the corresponding slider.