Problem 5: (II) Three point charges are arranged at the corners of a square of side l as shown in Fig. 17–39. What is the poten- tial at the fourth corner (point A)? FIGURE 17-39 Problem 22. l +Q -20 l l +30 A l

An object has a charge of 35 nC. How many excess protons does it have?

(II) Three point charges are arranged at the corners of a square of side l as shown in Fig. 17–39. What is the poten- tial at the fourth corner (point A)? +Q -2Q FIGURE 17-39 +3Q A Problem 22.

(II) Point a is 62 cm north of a –3.8 µC point charge, and point b is 88 cm west of the charge (Fig. 17–40). Determine (a) Vý – Va and (b) Ep – Ea (magnitude and direction). 62 cm FIGURE 17-40 b Q =-3.8 µC Problem 27. 88 cm

2%. (II) Point a is 62 cm north of a -3.8 uC poini charge, atld point b is 88 cm west of the charge (Fig. 17-40). Determine (a) ½ - V, and (b} Ể, - Ê, {magnitude and direction). 62 cm FIGURE 17-40 b Problem 27. Q=-3.8 µC 88 cm

(III) Two equal but opposite charges are separated by a distance d, as shown in Fig. 17-41. Determine a formula for VBA = VB - Va for points B and A on the line between the charges situated as shown. -d - FIGURE 17-41 -b- +q b- B Problem 30. A -9

(II) You are given two unknown point charges, Q1 and Q2 . At a point on the line joining them, one-third of the way from Q to Q2 , the electric field is zero (Fig. 16–59). What is the ratio Q1/Q2? E= 0 Qi 3 Q2 FIGURE 16–59 Problem 34. l-

(II) Determine the direction and magnitude of the electric field at the point P in Fig. 16–56. The charges are separated by a distance 2a, and point P is a distance x from the midpoint between the two charges. Express your answer in terms of Q, x, a, and k. +Q а -Q FIGURE 16–56 Problem 31.

Determine the direction and magnitude of the electric field at point P, Fig. 16–69. The two charges are separated by a dis- tance of 2a. Point Pis on the perpendicular bisector of the line joining the charges, a distance x from the midpoint between them. Express your answers in terms of Q, x, a, and k. +Q FIGURE 16–69 a -Q Problem 66.

(II) Determine the electric field É at the origin 0 in Fig. 16–58 due to the two charges at A and B. y |+26 µC A 8.0 cm -26 µC B 8.0 cm FIGURE 16-58 8.0 cm Problem 33.