Chapter 22

1. Chapter 22 Electrostatics

2. The net charge of an atom equals • the number of protons in its nucleus. • the number of electrons surrounding its nucleus. • zero if the atom is electrically neutral. • always zero.

3. The net charge of an atom equals • the number of protons in its nucleus. • the number of electrons surrounding its nucleus. • zero if the atom is electrically neutral. • always zero.

4. If a neutral atom has 22 protons in its nucleus, the number of surrounding electrons is • less than 22. • 22. • more than 22. • sometimes any of these in a neutral atom.

5. If a neutral atom has 22 protons in its nucleus, the number of surrounding electrons is • less than 22. • 22. • more than 22. • sometimes any of these in a neutral atom. Comment: Any atom with 22 protons in its nucleus with more or less than 22 electrons is not neutral.

6. When we say charge is conserved, we mean that charge can • be saved, like money in a bank. • not be created or destroyed. • be created or destroyed, but only in nuclear reactions. • take equivalent forms.

7. When we say charge is conserved, we mean that charge can • be saved, like money in a bank. • not be created or destroyed. • be created or destroyed, but only in nuclear reactions. • take equivalent forms. Explanation: Electric charge cannot be created or destroyed. It can only be transferred from one place to another.

8. A negative ion has more • electrons than neutrons. • electrons than protons. • protons than electrons. • neutrons than protons plus electrons.

9. A negative ion has more • electrons than neutrons. • electrons than protons. • protons than electrons. • neutrons than protons plus electrons.

10. According to Coulomb’s law, the force between a pair of charged particles that are brought closer together • decreases. • increases. • increases only if the charges are of the same sign. • increases only if the charges are of opposite signs.

11. According to Coulomb’s law, the force between a pair of charged particles that are brought closer together • decreases. • increases. • increases only if the charges are of the same sign. • increases only if the charges are of opposite signs.

12. When a pair of charged particles are brought twice as close to each other, the force between them becomes • twice as strong. • 4 times as strong. • half as strong. • one-quarter as strong.

13. When a pair of charged particles are brought twice as close to each other, the force between them becomes • twice as strong. • 4 times as strong. • half as strong. • one-quarter as strong. Comment: In accord with the inverse-square law.

14. Unlike Newton’s law of gravity, Coulomb’s law involves • force at a distance. • a proportionality constant. • an inverse-square law. • repulsive as well as attractive forces.

15. Unlike Newton’s law of gravity, Coulomb’s law involves • force at a distance. • a proportionality constant. • an inverse-square law. • repulsive as well as attractive forces.

16. When you scuff electrons off a rug with your shoes, your shoes become • negatively charged. • positively charged. • ionic. • electrically neutral.

17. When you scuff electrons off a rug with your shoes, your shoes become • negatively charged. • positively charged. • ionic. • electrically neutral.

18. When a cloud that is negatively charged on its bottom and positively charged on its top moves over the ground below, the ground acquires • a negative charge. • a positive charge. • no charge since the cloud is electrically neutral. • an electrically grounded state.

19. When a cloud that is negatively charged on its bottom and positively charged on its top moves over the ground below, the ground acquires • a negative charge. • a positive charge. • no charge since the cloud is electrically neutral. • an electrically grounded state.

20. When a negatively charged balloon is placed against a wooden door, positive charges in the wall are • attracted to the balloon. • repelled from the balloon. • too bound to negative charges in the door to have any effect. • neutralized.

21. When a negatively charged balloon is placed against a wooden door, positive charges in the wall are • attracted to the balloon. • repelled from the balloon. • too bound to negative charges in the door to have any effect. • neutralized.

22. If it takes 10 newtons of force to hold a 0.1-coulomb particle at rest in an electric field, the strength of the field there is • 1 N/C. • 10 N/C. • 100 N/C. • 1000 N/C.

23. If it takes 10 newtons of force to hold a 0.1-coulomb particle at rest in an electric field, the strength of the field there is • 1 N/C. • 10 N/C. • 100 N/C. • 1000 N/C.

24. In the electric field surrounding a group of charged particles, field strength is greater where field lines are • thickest. • longest. • farthest apart. • closest.

25. In the electric field surrounding a group of charged particles, field strength is greater where field lines are • thickest. • longest. • farthest apart. • closest.

26. Electrons on the surface of a conductor will arrange themselves such that the electric field • inside cancels to zero. • follows the inverse-square law. • tends toward a state of minimum energy. • is shielded from external charges.

27. Electrons on the surface of a conductor will arrange themselves such that the electric field • inside cancels to zero. • follows the inverse-square law. • tends toward a state of minimum energy. • is shielded from external charges.

28. The change in potential energy of a charged object depends on • the work done on it. • its location. • its mass. • both mass and location.

29. The change in potential energy of a charged object depends on • the work done on it. • its location. • its mass. • both mass and location.

30. Normally, a rubber balloon charged to thousands of volts has a relatively • large amount of charge. • small amount of energy. • small electric potential. • small electric field.

31. Normally, a rubber balloon charged to thousands of volts has a relatively • large amount of charge. • small amount of energy. • small electric potential. • small electric field.

32. A superconductor has the property of • changing from a conductor to an insulator. • becoming conducting when illuminated with light. • having a low electrical resistance. • All of the above.

33. A superconductor has the property of • changing from a conductor to an insulator. • becoming conducting when illuminated with light. • having a low electrical resistance. • All of the above. Comment: Don’t confuse a superconductor with a semiconductor!

34. Electric potential and electric potential energy are • one and the same in most cases. • two terms for the same concept. • Both of these. • None of these.

35. Electric potential and electric potential energy are • one and the same in most cases. • two terms for the same concept. • Both of these. • None of these. Explanation: Electric potential is electric potential energy per charge, a ratio of energy per charge in units joules per coulomb (volts). Electric potential energy has units of joules.

36. Voltage is electric potential energy per charge measured in units of • volts. • joules. • coulombs. • amperes.

37. Voltage is electric potential energy per charge measured in units of • volts. • joules. • coulombs. • amperes.

38. The thing that we measure in joules per coulomb is • electric force. • electric field. • electric current. • voltage.

39. The thing that we measure in joules per coulomb is • electric force. • electric field. • electric current. • voltage.

40. A capacitor can store • charge. • energy. • Both. • Neither.

41. A capacitor can store • charge. • energy. • Both. • Neither.