Click here to go to the applet.

This applet demonstrates electrostatics in two dimensions. There is also a three dimensional applet which is more accurate but less flexible.

When the applet starts up you will see the electric field of two positive charges. The yellow circle represents the charge; the white circles around it are equipotential lines (lines of constant potential). The field lines are also drawn in white. The green arrows indicate the electric field. The charge can be dragged around the screen with the mouse.

In general, yellow represents positive charge, and blue represents negative charge.

Conductors, dielectrics, and media with bound charges will show up as gray. Click on the objects, or the outer edge of the objects, to see what type they are.

Since this is a 2-D simulation, the electric field of charges is proportional to 1/r, like a line charge, not 1/r2 like a point charge. It should be treated as a 2-D cross section, where all the charges and conductors extend in and out of the screen.

The Example popup can be used to view some interesting pre-defined experiments. Once an experiment is selected, you may modify it all you want. The choices are:

The Show popup determines which fields or other quantities to display, and how to display them.

The Show Equipotentials checkbox draws equipotential lines, which are lines of constant potential.

The Brightness slider controls the brightness, just like on a TV set. Also when the brightness is higher it causes more equipotentials to be drawn.

The Equipotential Count slider allows you to control the number of equipotentials independently from the brightness.

Click here to go to the applet.