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Unformatted text preview: ELECTRIC CHARGE AND ELECTRIC FIELD 17
10. B 11. D 12. A 13. B 14. C 15. A Answers to Multiple-Choice Problems
1. D 2. C 3. C 4. B, C 5. E 6. B 7. C 8. A 9. B Solutions to Problems
17.1. Set Up: Unlike charges attract and like charges repel. In a conductor some of the negative charge is free to
move. In an insulator the charge can shift position only slightly. Solve: (a) Aluminum is a conductor and negative charge in the sphere moves away from the rod. The distribution of charge is sketched in Figure 17.1a. (b) The charges in the nonconducting sphere displace slightly, with negative charge moving away from the rod. The distribution of charge is sketched in Figure 17.1b. (a) (b) Figure 17.1 17.2. Set Up: Copper is a conductor, so some of the electrons are free to move. The positive charge on the rod attracts the negative charge in the ball. When the ball is connected to the earth by a conducting wire, charge can ﬂow between the ball and the earth. Solve: (a) Electrons move toward the rod. The distribution of charge is sketched in Figure 17.2a. (b) Electrons from the earth are attracted by the region of positive charge on the ball and ﬂow onto the ball, giving it a net negative charge. When the rod is removed, this net charge distributes uniformly over the surface of the ball, as sketched in Figure 17.2b. (a) (b) Figure 17.2 17.3. Set Up: For an isolated sphere, the excess charge is uniformly distributed over the surface of the conductor.
Unlike charges attract and like charges repel, and in a conductor the excess charge is free to move. Solve: (a) The uniform distribution of charge over the surface of each sphere is sketched in Figure 17.3a. (b) When the spheres are close to each other, the negative and positive excess charges are drawn toward each other, as shown in Figure 17.3b. 17-1 ...
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This note was uploaded on 03/06/2009 for the course PHYS 114 taught by Professor Shoberg during the Spring '07 term at Pittsburg State Uiversity.
- Spring '07