Review Conceptual Example 7 as background for this problem. A positive charge +q1 is located to the left of a negative charge -q2. On a line passing though the two charges, there are two places where the total potential is zero. The rst place is between the charges and is 2.82 cm to the left of the negative charge. The second place is 6.63 cm to the right of the negative charge. (a) What is the distance between the charges? lb) Find q1/q2, the ratio of the magnitudes of the charges. V = O V V = O V w\\@\\ LaJ (a) Number n Units 6 4} (b) Number n Units A positive point charge (q = +9.23 x 10-8 C) is surrounded by an equipotential surface A, which has a radius of rA = 2.38 m. A positive test charge (qo = +4.97 x 10-1 C) moves from surface A to another equipotential surface B, which has a radius . The work done by the electric force as the test charge moves from surface A to surface B is WAB = -6.51 x 10-9 J. Find rB. IB = iThe capacitance of an empty capacitor is 7.70 [JR The capacitor is connected to a 12-V battery and charged up. With the capacitor connected to the battery, a slab of dielectric material is inserted between the plates. As a result, 9.00 x 10'5 C of additional charge ows from one plate, through the battery, and onto the other plate. What is the dielectric constant of the material? Number I Units 6