Physics 100-Chapter 22 questions

27. How does one coulomb of charge compare with the charge of a single electron? a) A coulomb of charge is the charge associated with 6.25 × 1018 electrons. b) A coulomb of charge is the charge associated with half the charge of 6.25 × 10 -18 electrons. c) A coulomb of charge is the charge associated with 1.6 × 1019 electrons. d) A coulomb of charge is the charge associated with 1.6 × 10 -19 electrons.

-a) a coulomb of charge is the charge associated with 6.25 x 1018 electrons

14. Which force binds atoms together to form molecules? a) electrical b) centripetal c) nuclear d) gravitational e) none of these

-a) electrical

21. The fundamental force underlying all chemical reactions is a) electrical. b) centripetal. c) nuclear. d) gravitational. e) None of the above choices are correct.

-a) electrical

2. If the atoms of one object (initially neutral) have electrons rubbed off through friction with a second object, the first object becomes ________. a) positively charged b) negatively charged c) neutral in charge d) It's impossible to say.

-a) positively charged -Since electrons are negatively charged, removing electrons from at atom causes the atom to become positively charged.

17. When the distance between two charges is halved, the electrical force between the charges a) quadruples. b) doubles. c) is reduced by 1/4. d) halves. e) None of the above choices are correct.

-a) quadruples

7. Consider the situation in the figure below, where two charged rods are placed a distance on either side of an aluminum can. What does the can do? a) Stays still b) Rolls to the left c) Rolls to the right

-a) stays still -The positively charged rod induces a negative charge on the left side of the can, creating an attractive force between the rod and the can. However, the negatively charged rod induces an equal positive charge on the right side of the can, which creates an attractive force between the can and that rod. The net force acting on the can is zero.

20. What would happen to the two balls if one of them were kept positively charged and the charge on the other ball were slowly made increasingly negative? a) The balls would begin to move closer together. b) The balls would not move relative to each other. c) The balls would begin to move farther apart.

-a) the balls would begin to move closer together

19. What would happen to the two balls if one of them were kept positively charged and the charge on the other ball were slowly increased, making it more and more positive? a) The balls would begin to move farther apart. b) The balls would not move relative to each other. c) The balls would begin to move closer together.

-a) the balls would soon begin to move farther apart

11. When we say charge is conserved, we mainly mean that charge can be _______. a) transferred without loss, like money in a bank b) saved, like money in a bank c) created and destroyed in equal amounts d) constant in all bodies

-a) transferred without loss, like money in a bank

13. The net charge on a polarized molecule is normally _______. a) zero b) the same as the charge that produces the polarization c) reoriented d) opposite to the charge that produces the polarization

-a) zero

12. Coulomb's law is most similar to which of these laws? a) the conservation of energy b) Newton's law of gravity c) the law of electric potential d) Archimedes' laws of hydrostatics

-b) Newton's law of gravity

24. The electrical force between charges is strongest when the charges are a) far apart. b) close together. c) The electric force is constant everywhere.

-b) close together

1. What causes an atom to become positively charged? a) Protons were added b) Electrons were removed c) Either protons were added, or electrons were removed d) Electrons were added

-b) electrons were removed -Removing an electron causes the atom to have more protons, which have a positive charge, than electrons, which have a negative charge.

9. Using the setup from the first question, imagine that you briefly touch the negatively charged rod to the can. You then hold the two rods at equal distances on either side of the can. What does the can do? a) Rolls away from the positively charged rod b) Rolls toward the positively charged rod c) Does not move

-b) rolls toward the positively charged rod -The can acquires a net negative charge after being touched, so it is then attracted to the positively charged rod.

8. Now, consider the situation shown in the figure below. What does the can do? a) rolls to the left b) stays still c) rolls to the right

-b) stays still -The polarization force is always attractive, so the can does not move.

16. A balloon will stick to a wooden wall if the balloon is charged a) negatively. b) positively. c) either positively or negatively. d) None of the above choices are correct.

-c) either positively or negatively

3. The basic reason why things become electrically charged is that the atoms (or molecules) of some materials hold on to their _______ better than those of other materials. a) protons b) neutrons c) electrons

-c) electrons -The outer electrons of atoms of certain materials are very weakly bonded, so they can easily be ripped off and transferred to other materials.

23. To say that electric charge is quantized is to say that the charge on an object a) will interact with neighboring electric charges. b) may occur in an infinite variety of quantities. c) is a whole-number multiple of the charge of one electron. d) is sometimes positive. e) can be neither created nor destroyed.

-c) is a whole-number multiple of the charge of one electron

25. The electrical force between charges depends only on the charges' a) separation distance. b) magnitude. c) magnitude and separation distance. d) None of the above choices are correct.

-c) magnitude and separation distance

26. Rub electrons from your hair with a comb and the comb becomes a) positively charged. b) discharged. c) negatively charged.

-c) negatively charged

5. Object A is attracted to object B and repelled by object C. All three objects are charged. What would happen if object B and object C were brought together? a) They would be neither repelled nor attracted to each other. b) They would be repelled by each other. c) They would be attracted to each other.

-c) they would be attracted to each other -Since one object is attracted to object A and one object is repelled by object A, either object B is positively charged and object C is negatively charged, or visa versa.

18. Two charges separated by one meter exert 1-N forces on each other. If the charges are pulled to 3-m separation distance, the force on each charge will be a) 0.33 N. b) 9 N. c) 0 N. d) 0.11 N. e) 3 N.

-d) 0.11 N

4. If the distance between two charged objects is doubled, the resulting electric force on each object __________. a) increases by a factor of 2 b) decreases by a factor of 2 c) increases by a factor of 4 d) decreases by a factor of 4

-d) decreases by a factor of 4 -Just like gravity, the electric force is inversely proportional to the square of the distance between the particles

10. Most atoms normally have a net charge that is _______. a) positive b) negative c) positive in the nucleus and slightly more negative in the electrons d) zero

-d) zero

15. The unit of electric charge, the coulomb, is the charge on a) a neutron. b) one electron. c) a specific number of neutrons. d) a quark. e) a specific large number of electrons.

-e) a specific large number of electrons

22. A positive ion has more a) electrons than neutrons. b) electrons than protons. c) neutrons than protons. d) protons than neutrons. e) protons than electrons.

-e) protons than electrons

6. Object A and object B are both hanging by a string, as shown in the figure. Which statement must be true? a) Object A and object B must have the same net charge. b) Both objects must be positively charged. c) Object A and object B must have opposite charges. d) Both objects must be charged, either both negatively or both positively. e) More than one of the above statements are true.

d) both objects must be charged, either both negatively or both positively -Like charges are repelled by each other; it is impossible to determine whether both objects are negatively charged or positively charged based on the information given.