第一題

1. When a glass rod is rubbed with silk cloth, the rod becomes positively charged as

第二題

2. Which of the following terms is used to describe a material that does not allow electrons to easily move through it?

第三題

3.Three identical conducting spheres on individual insulating stands are initially electrically neutral. The three spheres are arranged so that they are in a line and touching as shown. A negatively-charged conducting rod is brought into contact with sphere A. Subsequently, someone takes sphere C away. Then, someone takes sphere B away. Finally, the rod is taken away. What is the sign of the final charge, if any, of the three spheres? BallA BallB Ball C

第四題

4. Consider the conducting spheres labeled A, B, and C shown in the drawing. The spheres are initially charged as shown on the left, then wires are connected and disconnected in a sequence shown moving toward the right. What is the final charge on sphere A at the end of the sequence?

第五題

5. Two point charges are stationary and separated by a distance R. Which one of the following pairs of charges would result in the largest repulsive force?

第六題

6. The drawing shows a hollow conducting sphere with a net positive charge uniformly distributed over its surface. A small negatively-charged object has been brought near the sphere as shown. What is the direction of the electric field at the center of the sphere?