
A pair of point charges with opposite sign create a dipole field.
The Point Charge Electric Fields model shows the electric field from multiple point charges. The particle xy-positions and charge are stored in 10-element arrays but fewer this maximum number are usually displayed. Only the first n particles are visible and only these active particles are used to compute the field. The Add Particle button in the control panel increments the number of particles and the Reset button removes all charges. Whenever a charge is added or moved, the electric field is recomputed using a fixed relation.
The following EJS models are described in Chapter 10 of the EJS adaptation of An Introduction to Computer Simulation Methods.
Additional models to be written.
The Point Charge Electric Fields model was created by Wolfgang Christian using the Easy Java Simulations (EJS) modeling tool version 4.2. You can examine and modify the model for this simulation if you have EJS installed by right-clicking within the program and selecting "Open Ejs Model" from the pop-up menu.
Information about EJS is available at: <http://www.um.es/fem/Ejs/> and in the OSP ComPADRE collection <http://www.compadre.org/OSP/>.