++ + B ++ A Figure 4 C 10 V P2 OV 91 X -10 V P4 92 Figure 5 OV -10 V 10 V Figure 6 P3 7. Figure 4 shows a region between two metal plates that have been charged to a potential difference of 45 V. Which has the higher electric potential, point A or point B? 8. The points A, B, and C in Figure 4 form a right triangle and each are just outside the metal surfaces. The size of the gap is 0.50 mm, so the electric field between the plates is 90 000 V/m. What work is done by an external agent to slowly move a proton from point A to point B? 9. If the area of each of the metal plates in Figure 4 is 0.125 m² and the gap b gap between the plates is filled with a dielectric material such as Teflon that has a relative permittivity k = 2.1. What is the capacitance of this capacitor? 200 10. (a) What amount of charge and (b) what amount of energy is stored in a 140 uF capacitor if it was fully charged by a 12V battery? 11. Figure 5 shows two charges (91 = 25 nC and 92 = -55 nC) separated by a distance of 6.0 mm. The charges are arranged along the y axis, equidistant from the origin. What is the value of the electric potential at the point (4.0 mm, 0) on the x axis? 12. What is the electric potential energy of the system in Figure 5 using the charge values given in the previous question? 13. In Figure 6 above shows four charges A, B, C, and D and the equipotential lines around those charges. It also shows four labeled points in the space near the charges: P1, P2, P3, and P4. (a) (a) Is charge C positive, negative, or neutral? (b) At which of the labeled points in Figure 6 has the electrostatic potential the greatest? (c) At which of the labeled points in Figure 6 is the electric field the strongest? (d) What is the potential difference between P3 and P4?