Quiz

QUIZ

1. What is true of electrical charges and electrical forces?

a. Positive charges attract each other with a force that increases with distance. b. Positive and negative charges attract each other with a force that decreases with distance. c. Positive and negative charges repel each other with a force that increases with distance. d. Negative charges attract each other with a force that decreases with distance.

Answer: b. Positive and negative charges attract each other with a force that will decrease with distance. There are just two types of charges, positive and negative with opposites attracting each other. The force of electricity between two things will decrease with the distance between them.

2. What is considered the smallest unit of charge in nature?

a. One proton or one electron b. One proton c. One electron d. One coulomb

Answer: a. The smallest unit of charge in nature is the charge on one proton or one electron, which have equal charges (although they are opposite in sign). It takes 6.25 x 1018 charges to make a coulomb of charge.

3. What is the charge on a quark?

a. Plus one b. Minus 1/3 c. Minus one d. Plus 2/3 or minus 1/3

Answer: d. The charge on the quark can be either plus 2/3 or minus 1/3. These are partial charges that together make up the plus one charge of a proton. Quarks are the sub-particles that make up the totality of a proton, although they have not truly been “seen”—only suspected to be there.

4. What is not considered conserved in the laws of physics?

a. Forces b. Energy c. Charge d. Momentum

Answer: a. Each of these are considered conserved, including that of angular and linear momentum with the exception of force and forces, which are not conserved in physics. From an electrical standpoint, electric charges are conserved.

5. What is the charge on an ion in physical chemistry?

a. It is neutral b. It can be positive or negative c. It is negative d. It is positive

Answer: b. An ion can be positively-charged or negatively-charged. Anions, by definition, are negatively charged, while cations are, by definition, considered to be positively charged atoms or molecules.

6. What is the overall charge on a polarized object?

a. It depends on the other object that is polarizing it and the charge of the other object. b. It will be negatively charged. c. It will be positively charged. d. It will be neutral.

Answer: d. While a polarized object will have a partial positive charge on one side and a partial negative charge on the other side, it will be neutral overall even though it is polarized.

7. What are the SI units for the electric field?

a. Joules b. Coulombs c. Joules per coulomb d. Joule coulombs

Answer: c. The SI units for electric field are joules per coulomb as it is defined as the force divided by the test charge.

8. What is the direction and magnitude of an electric field charge?

a. The direction is toward the positive charge and directly proportional to the area involved. b. The direction is toward the positive charge and inversely proportional to the area involved. c. The direction is toward the negative charge and directly proportional to the area involved. d. The direction is toward the negative charge and inversely proportional to the area involved.

Answer: d. By convention, the direction of an electric, magnetic, or electrostatic field charge is toward the negative charge and is inversely proportional to the area involved. When the lines of the electrostatic

field are closer together, the field is considered stronger because the area is bigger.

9. What is not true of an electric field that has a conductor placed within it?

a. The field within the conductor itself will be zero. b. The field extends outward from the positive charge of the conductor. c. The field will polarize the conductor. d. The field lines will be parallel to the conductor.

Answer: d. The field lines will be zero in the conductor and will extend outward from the positive charge of the conductor or toward the negative charge of the conductor. The conductor will be polarized by the electric field; however, the field lines will emanate perpendicular to and not parallel to the conductor itself.

10. What creates the negative electric charge around the earth?

a. Storm clouds b. The moon c. The ionosphere d. The sun

Answer: c. The ionosphere is a layer of positive charge about 100 kilometers around the earth, causing a field with the earth as the negatively-charged object.