Homework 9 Exam-Type Questions - Chapter 19

1. Which of the following can be used to charge a metal rod that is held in your hand? Rub it with

a. fur.
b. silk.
c. wool.
--> d. It can't be done.

2. We are led to believe that there were two kinds of charge because we are able to

a. isolate them in separate containers.
--> b. see two effects, attraction and repulsion.
c. detect different weights for the same object.
d. separate electrons and protons.

3. Which of the following objects are attracted by a positively charged object?

a. only positively charged objects
b. only negatively charged objects
c. only neutral objects
--> d. neutral and negatively charged objects

4. Which of the following sets of hypothetical observations about an object would demonstrate the existence of a third kind of electric charge?

a. It repels positive and attracts negative charges.
b. It attracts positive and repels negative charges.
c. It attracts positive and negative charges.
--> d. It attracts positive and negative charges and repels itself.

5. Two identical electroscopes, one initially charged and the other initially neutral, are connected by a thin rod. If both electroscopes are now charged, you can conclude that

--> a. the rod is a conductor.
b. they have opposite charges.
c. the rod is an insulator.
d. one electroscope is grounded.

6. Two parallel plates have equal but opposite charges. The electric force on a negative charge placed near the center of the plates is

--> a. perpendicular to the plates and points toward the positive one.
b. perpendicular to the plates and points toward the negative one.
c. parallel to the plates.
d. zero.

7. Two charged objects are very, very far from any other charges. If the distance between them is doubled, the electric force between them

a. doubles.
b. is cut in half.
--> c. is 1/4th as large.

8. Two charged objects are very, very far from any other charges. If the charge on one of them is doubled while the other is cut in half, the electric force between them

a. doubles.
b. is cut in half.
--> c. stays the same.

9. Even though electric forces are very much stronger than gravitational forces, gravitational forces determine the motions in the solar system because

a. electric forces have a longer range than gravitational ones.
b. electric forces have a shorter range than gravitational ones.
c. the electric forces do not act through a vacuum.
--> d. the electric forces cancel due to the two kinds of charge.

10. Which of the following statements about the electric and gravitational forces is wrong?

a. Gravitational mass is proportional to mass, but electric
charge is not proportional to mass.
b. Gravitational forces are always attractive while electric ones
can be attractive or repulsive.
c. Electric charge comes in multiples of one size while gravitational
mass comes in multiples of many different sizes.
--> d. The electric force decreases more rapidly with distance than the
gravitational force.

11. The force that holds atoms together is

a. magnetic.
b. gravitational.
--> c. electric.
d. unknown to scientists.

12. The electric field around an isolated negative charge

a. points outward.
b. forms clockwise circles about the charge.
--> c. points inward.
d. forms counterclockwise circles about the charge.

13. The numerical value of the electric potential energy at each point in space is defined to be the

a. work required to bring a charged object from the zero point.
b. average force required to bring a charged object from the
zero point.
c. energy required to bring a unit of positive charge from the
zero point.
--> d. work required to bring a unit of positive charge from the
zero point.

14. Points A and B each have an electric potential of +12 V. How much work would be required to take 4 C of positive charge from A to B?

--> a. zero
b. 3 J
c. 8 J
d. 48 J

R.S. Panvini
12/4/2000