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Unformatted text preview: honea (cth632) H1ElectriFields avram (1956) 1 This print-out should have 23 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. 001 10.0 points A plastic rod is rubbed against a wool shirt, thereby acquiring a charge of 4 . 9 C. The charge on an electron is 1 . 6 10 19 C. How many electrons are transferred from the wool shirt to the plastic rod? Correct answer: 3 . 0625 10 13 . Explanation: Let : q = 4 . 9 C = 4 . 9 10 6 C and e = 1 . 6 10 19 C . The total charge is q = n e e n e = q e = 4 . 9 10 6 C 1 . 6 10 19 C = 3 . 0625 10 13 . 002 10.0 points When a positively charged conductor touches a neutral conductor, the neutral con- ductor will 1. stay neutral. 2. gain electrons. 3. lose protons. 4. lose electrons. correct 5. gain protons. Explanation: When the two conductors touch, the elec- trons in the neutral conductor will move over to the positively charged conductor, since the latter will define a region of higher potential than the neutral conductor. 003 10.0 points Two uncharged metal balls, Z and X , stand on insulating glass rods. A third ball, carrying a positive charge, is brought near the ball X as shown in the figure. A conducting wire is then run between Z and X and then removed. Finally the third ball is removed. X Z + conducting wire When all this is finished 1. ball Z is negative and ball X is neutral. 2. balls Z and X are both negative, but ball X carries more charge than ball Z . 3. ball Z is neutral and ball X is negative. 4. ball Z is positive and ball X is negative. correct 5. balls Z and X are still uncharged. 6. ball Z is negative and ball X is positive. 7. ball Z is neutral and ball X is positive. 8. balls Z and X are both negative, but ball Z carries more charge than ball X . 9. balls Z and X are both positive. 10. ball Z is positive and ball X is neutral. Explanation: When the conducting wire is run between Z and X , some positive charge flows from X to Z under the influence of the positive charge of the third ball. Therefore, after the wire is removed, Z is charged positive and X is charged negative. 004 10.0 points Two electrostatic point charges of +62 . C and +56 . C exert a repulsive force on each honea (cth632) H1ElectriFields avram (1956) 2 other of 158 N. What is the distance between the two charges? The Coulomb constant is 8 . 98755 10 9 N m 2 / C 2 . Correct answer: 0 . 444408 m. Explanation: Let : q 1 = 62 . C , q 2 = 56 . C , F electric = 158 N , and k C = 8 . 98755 10 9 N m 2 / C 2 . F electric = k C q 1 q 2 r 2 r = radicalBigg k C q 1 q 2 F electric = radicalBig 8 . 98755 10 9 N m 2 / C 2 radicalbigg (6 . 2 10 5 C) (5 . 6 10 5 C) 158 N = . 444408 m ....
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