Physics 011

Answers of PQ#16

 1. Electrons carry a  The correct answer: negative charge. Review Section 16-2 in Giancoli. 2. The units of Coulomb's constants are  The correct answer: Nm2/C2 Review Section 16-5 in Giancoli. 3. The units of permittivity are  The correct answer: C2/Nm2 It is the reciprocal of Coulomb's constant. Review Section 16-5 in Giancoli. 4. The unit of a charge is the Your answer: C(oulomb) 5. Which of the following are the units of electric field? The correct answer: N/C Review Section 16-7 in Giancoli. 6. Two charges Q1 and Q2 are separated by a distance D. If the distance is doubled, the force is  The correct answer: decreased by a factor of 4. Close but it will decrease. Review Section 16-5 in Giancoli. 7. Two charges Q1 and Q2 are separated by a distance D. If Q1 is doubled, the force is Your answer: increased by a factor of 2. 8. Two charges Q1 and Q2 are separated by a distance D. If Q1 and Q2 are doubled, the force is  The correct answer: increased by a factor of 4. This would be true if only one was doubled. Review Section 16-5 in Giancoli. 9. Two charges Q1 and Q2 are separated by a distance D. If both Q1 and D are doubled, the force is  The correct answer: decreased by a factor of 2. Review Section 16-5 in Giancoli. 10. Two charges Q1 and Q2 are separated by a distance D. If Q1, Q2 and D are all doubled, the force is  The correct answer: remains the same. Review Section 16-5 in Giancoli. 11. In the above figure, if Q1 is negative and has magnitude less than Q2 which is positive, where could a positive charge be placed and possibly have a zero net force on it? Your answer: A 12. In the above figure, if Q1 and Q2 are positive, where could a negative charge be placed and have a vertically upward net force on it?  The correct answer: D Review Section 16-4 in Giancoli. 13. In the above figure, if Q1 and Q2 are positive, where would the electric field be vertically upward ?  The correct answer: B Review Example 16-8 in Giancoli. 14. In the above figure, if Q1 and Q2 are positive and the same size, where would the electric field be zero ?  The correct answer: E Review Example 16-7 in Giancoli. 15. In the above figure, if Q1 is negative and Q2 is positive and are both the same magnitude, where would the electric field be zero ?  The correct answer: Nowhere shown. Review Example 16-8 in Giancoli. 16. In the above figure, if Q1 is negative and Q2 is positive and the distance from Q2 to point C is 1/4 the distance between the charges, how many times greater than Q2 in magnitude must Q1 be for the Electric field to be zero at C?  The correct answer: 25 Q1 is 5 times further away. Review Section 16-7 in Giancoli. 17. In the above figure if the vertical distance from point E to B is the same as the horizontal distance from E to either charge and the electric field at B from either charge has magnitude 1.0x106, what is the magnitude of the net electric field?  The correct answer: 1.4x106 They are not colinear. Review Example 16-8b in Giancoli. 18. In the above figure the vertical distance from point E to B is the same as the horizontal distance from E to either charge and the electric field at B from either charge has magnitude 1.0x106. If Q1 is negative and Q2 is positive what is the direction of the net electric field at B?  The correct answer: Horizontal and to the left. Review Example 16-8 in Giancoli. 19. In the above figure the vertical distance from point E to B is the same as the horizontal distance from E to either charge and the electric field at B from either charge has magnitude 1.0x106. If both Q1 and Q2 are positive what is the direction of the net electric field at B? Your answer: Vertical and up. 20. The figure above shows a metal shell surrounding a positive charge. What is the charge on the metal surface at b? Your answer: negative 21. The figure above shows a metal shell surrounding a positive charge. Which of the following statements is true?  The correct answer: The electric field at c is less than that at a and e. Review Section 16-9 in Giancoli. 22. In question 20 what would be the charge on the exterior surface (d)? Your answer: positive 23. Four people tell you they have a negative charge of a certain value. Which one is not telling the truth?  The correct answer: Mine is 1.90x10-18 Coulomb. Review Section 16-5 in Giancoli. 24. What must be the charge on each of two 100 kg spherical masses in order for the electrical force to equal the gravitational force?  The correct answer: 8.6 nanoC Review Section 16-5 in Giancoli. 25. How many electrons would it take to make up a charge of minus one millionth of a Coulomb? Your answer: 6.25x1012