[24 pts] Four charges located at the four corners of a rectangle as shown in the figure. Q is 20 nC. The net electrostatic force on q1 is zero. [Answer in 2 significant figures] q1 =-Q 94 6 cm 8 cm 92 93 = +Q a) [12 pts] What is the charge on q2 and q4? b) [9 pts] What is the magnitude of the net electrostatic force on q3? c) [6 pts] What is the net potential at the center of the rectangle