1) Three point charges with q = 7.5 C are located as shown. If L = 15 cm, determine the magnitude and direction of the total electric force acting on the point charge located at (0, -L). [K2, T5, C3] 2) A metal-coated table tennis ball with a mass of 2.1 g is suspended by an insulating thread. A similar table tennis ball touches the first, giving each ball an equal negative charge. When the two balls are separated horizontally by 5.0 cm, the string hangs at 15 with respect to the vertical. Determine approximately how many excess electrons are on each table tennis ball. [K3, A5, C3] 15% 5.0 cm 3) Four point charges, each with a magnitude of 1.00 uC, are placed at the corners of a 45 rhombus with sides of length 1.0 m. Calculate the electric potential energy of the system. [K2, T5, C3] 45