The model allows investigate the interaction of electric charges. You can drag the charges to change their disposition and see how the distance between the charges influence on the force magnitude. Using floating band control you can vary the magnitude of the charge and it?s sign. Make sure that the force that one charge exerts on the other is equal to the magnitude of the force that the other charge exerts on the first. Investigate different cases of charges? signs and pay attention to the direction of the forces.