MC	Physics	Standard: 03
Objective: 02. Describe the factors that affect the electric force.
ILO:

The force between two static charges is +4N. The force is:

a. repulsive

b. attractive

c. can't tell

Correct Answer: a

MC	Physics	Standard: 03
Objective: 02. Describe the factors that affect the electric force.
ILO:

In a professional automobile paint shop, an electric charge is created on the surface of the automobile, and an electric charge is created on the tiny paint particles that are to be applied. This will help create a better paint job on the automobile. Using what you understand about electric charges, which of the following best explains why this would be done?

a. The two electric charges are the same so the paint will be attracted to the car.

b. The two electric charges are different so the paint will be attracted to the car.

c. The two electric charges are the same so the paint will be repelled from the car.

d. The two electric charges are different so the paint will be repelled from the car.

Correct Answer: b

E	Physics	Standard: 03
Objective: 02. Describe the factors that affect the electric force.
ILO:

A ïpith ballÍ is a Styrofoam ball coated with graphite. You find yourself conducting an experiment in which a pith ball has an unknown electric charge. Your task is to determine the type of charge on the pith ball. The following materials are available to you:

Extra pith balls

Glass rod

Plastic rod

Silk

Fur

Paper

Write three paragraphs describing how you would determine the type of charge on the unknown pith ball. Be sure to indicate what evidence you would gather, and how that evidence leads you to your conclusions.

Scoring Guide:

Students should indicate the following:

• Like charges repel each other, and unlike charges attract each other.
• They can create a known electric charge by rubbing glass rod with silk, or by rubbing a plastic rod with fur.
• They should describe the creation of the known electric charge, then bringing that charge near the unknown pith ball to observe the effect. If the pith ball is attracted, it is opposite the known charge. If the pith ball is repelled, it is the same as the known charge.
• Students should explain what they would do using at least three paragraphs, and have correct spelling, grammar, and punctuation.