At a point where the electric potential is 400 V, a positive charge is moving to the left. As the charge continues to move, it slows down, stops, and then begins to move back to the right. Using what you learned in Figure 21.7, its speed as it passes its initial position is 

A. Greater than its initial speed. 

B. Less than its ini tial speed.

C. Equal to its initial speed. 

D. There is not enough information to tell.

Transcribed Image Text:

FIGURE 21.7 A charged particle speeds up or slows down as it moves through a potential difference. (a) A positive charge speeds up (AK > 0) as it moves from higher to lower potential (AV <0). Electric potential energy is transformed into kinetic energy. (b) A positive charge slows down (AK0) as it moves from lower to higher potential (AV>0). Kinetic energy is transformed into electric potential energy. 500 V Before: 400 V 500 V After: After: 400 V Before: AV=-100 V <0 Dashed green lines are lines of constant electric potential. The potential is 500 V at all points on this line. AV = +100 V >0 A double-headed green arrow is used to represent a potential difference.