The blue circles represent negative 1.0 nanoCoulomb (nC) charges. The red circles represent +1 nC charges. Move these circles to see the resulting changes in the electric field and electric potential map. Select one of the three charge configurations using the top three checkboxes. Move the yellow circle into the large square to measure the magnitude and direction of the Electric Field at any point. Move the green circle into the large square to measure the Electric Potential at any point. The electric field vectors show the relative strength of the electric field through their color. Where the field is strong the vectors are white and where it is weakest they are black.