10. Which scenario shows radiation?(1 point)
A. Eggs cook in a skillet.
B. The air under a reading lamp is warmed.
C. Eggs boil in a pot of water.
D. Air warmed by a floor radiator rises to the top of a room, forcing cooler air downward.
11. Which pair of objects will have an attractive electric force?
A. Pair D
B. Pair B
C. Pair C
D. Pair A
12. How does the structure of atoms in a substance determine the substance’s conductivity?
A. If an atom’s outer shell of electrons is tightly bound to the nucleus, the substance is a good conductor.
B. If an atom’s nucleus is positively charged, the substance is a good conductor.
C. If an atom’s outer shell of electrons is positively charged, the substance is a good conductor.
D. If an atom’s outer shell of electrons is loosely bound to the nucleus, the substance is a good conductor.
13. Students build four electromagnets and test them by picking up metal tacks. Here are their partial results.
12 coils 4 tacks
24 coils 9 tacks
36 coils 13 tacks
48 coils ? tacks
Which is the best prediction for the number of nails the electromagnet with 48 coils will pick up?
A. 12 tacks
B. 16 tacks
C. 20 tacks
D. 13 tacks
14. How do electromagnets cause a maglev train to levitate above the track?
A. Batteries provide electric energy to the electromagnets in the train.
B. Magnets in the sides of the tracks constantly repel and attract magnets in the sides of the train.
C. Magnets in the track and magnets in the bottom of the train repel each other.
D. Magnets in the track and magnets in the bottom of the train attract each other.
15. Which of these best describes the type of lens shown in the ray diagram?
A. It shows a concave lens. For this type of lens, the image position depends on the object's position relative to the focus point.
B. It shows a concave lens. For this type of lens, the image is always on the opposite side of the lens as the original object.
C. It shows a convex lens. For this type of lens, the image is always on the opposite side of the lens as the original object.
D. It shows a convex lens. For this type of lens, the image position depends on the object's position relative to the focus point.
10. B. The air under a reading lamp is warmed by radiation from the lamp.
11. D. Pair A has opposite charges and will attract each other due to electric force.
12. D. If an atom's outer shell of electrons is loosely bound to the nucleus, the substance is a good conductor because the electrons can move freely and carry electric current.
13. B. Using the trend in the data, we can estimate that the electromagnet with 48 coils will pick up approximately 16 tacks.
14. B. Magnets in the sides of the tracks and train constantly repel and attract each other, creating a magnetic field that causes the train to levitate above the track.
15. A. The ray diagram shows a concave lens, and the image position depends on the object's position relative to the focus point for this type of lens.