We consider a number of charges, which generate an electrostatic field in the given space. With this applet, we can study the properties of the field of these charges at any point the the screen.[br]The applet consists of 5 images to be selected with the slider "image":[br][br]1. Entry with controls: the number (6 maximum) of the charges, their respective strengths and positions (between -10 and +10) are set by the regulator for each charge.[br]The electric field can be tested with the test charge q. You can move this by dragging it with the mouse to any point of the drawing area. The arrow shows the direction of the field strength at this point.[br]The appropriate size of the potential φq, the magnitude of the field strength Eq and the coordinates of the point Aq(x,y) are displayed on the right side of the screen.[br]2. Description of the generated E-field by red-blue direction indicators.[br]3. Visualization of the generated E-field potential with equipotential lines. With animation by mouse click, the equipotential lines are drawn in color.[br]The test charge can be used to determine the potentials of the corresponding lines. The white line corresponds to the potential: φq = 0 V.[br]4. Creation of the field line images. The field lines are drawn around each charge. This representation must be considered as an approximation.[br]5. Vector field equipotentials and field lines will be shown together. You can clearly see that the equipotential lines are perpendicular to the electric field and that the electric field runs always from higher to lower potential.