Explain briefly why repulsion is a better test for the sign of a charged object than attraction is. A solid plastic ball has negative charge uniformly spread over its surface. Which of the diagrams...

Explain briefly why repulsion is a better test for the sign of a charged object than attraction is.

A solid plastic ball has negative charge uniformly spread over its surface. Which of the diagrams in Figure 15.71 best

shows the polarization of molecules inside the ball?

15.X.47 A charged piece of invisible tape is brought near your hand, as shown in Figure 15.72. Your hand is initially neutral.

(b) Which arrow in Figure 15.74 best indicates the direction (a–j) of the electric field at the location of the tape due to the large number of polarized molecules in your hand?