Choose the letter of the correct answer 1. Three pith balls supported by insulating threads hang from a support. We know that ball X is positively charged. When ball X is brought near balls Y and Z without touching them, it attracts Y and repels Z. We can conclude that: a. Y has a neutral charge. b. Y has a positive charge. c. Z has a negative charge. d. Z has a positive charge.

Choose the letter of the correct answer

1. Three pith balls supported by insulating threads hang from a support. We know that ball X is positively charged. When ball X is brought near balls Y and Z without touching them, it attracts Y and repels Z. We can conclude that:

a. Y has a neutral charge.

b. Y has a positive charge.

c. Z has a negative charge.

d. Z has a positive charge.

2. When you brush your hair on a cool, dry day, you might hear your hair crackling as it gets charged. Which of the following most likely explains what is happening?

a. Lightning is about to strike.

b. Electrons transfers from the air to the hair.

c. Electrons are added from the air to the brush.

d. Electrons transfer from the hair to the brush.

3. Several electrons are added to a conducting sphere. Which of the following statements is true?

a. The electric field inside the sphere is zero.

b. The electric field inside the sphere is uniform.

c. The electric field inside the sphere is directed inward.

d. The electric field inside the sphere is directed outward.

4. The electric field strength at 1 m from a point is 6 N/C. What is the electric field strength at a distance 2m from the same point charge?

a. 1.5 N/C c. 6 N/C

b. 3 N/C d. 12 N/C

5. The analogy of electric forces and gravitational forces is good EXCEPT.

a. electricity involves magnetism.

b. forces are conservative.

c. momentum does not apply in electricity.

d. charge can be positive or negative.

6. When charging two objects by rubbing them together:

a. Neither may be a conductor.

b. They must be made of different material.

c. They will sometimes end up with both being positively charged.

d. The heat produced by friction is a necessary part of this process.

7. The electric field at the surface of a positively charged conductor has a direction characterized by which of the following?

a. Tangent to the surface.

b. Perpendicular inward toward the charge.

c. At a 45-degree angle to the surface.

d. Perpendicular outward and away from the charge.

8. The electric field at the surface of a negatively charged conductor has a direction characterized by which of the following?

a. Tangent to the surface.

b. Perpendicular inward toward the charge.

c. At a 45-degree angle to the surface.

d. Perpendicular outward and away from the charge.