In the circuit shown, the capacitor C4 is unknown, and all the capacitors are initially discharged. The capacity of the equivalent capacitor between the two points A and B is: Ceq 12 F. = A C6 =18 F +V= 48 V I B C =9 F C =7 F C4 Cs = 11 F C = 70 F C3=8 F 1) Find the value of the capacity for the capacitor C4- 2) Determine the quantity of charge Q, the potential difference V, and the potential energy U of the capacitor C = 7 F.