To understand the idea of remote action, characteristic of force fields, we will choose the model of the elastic membrane. What would happen to a second ball which was put on the same surface? Wouldn't it be "pushed" by the deformation of the surface?

In a similar way, suppose that the electric charge of bodies alters the space around them. The magnitude which measures this change is the intensity of the electric field, the force exerted on a positively charged unit situated at a determined point. Click on to learn about some of its properties (do activities A.1, A.2, A3 and A.4 in the visual)