Four electrons move from point A to point B in a uniform electric field as shown below. Rank the electrons in diagrams I through IV by the changes in potential energy from most positive to most negative when traveling from A to B.

Question

Quizplus · Accepted Answer

The potential energy of a charged particle in a uniform electric field is given by U=qEd, where q is the charge, E is the electric field strength, and d is the distance moved in the field. Since all the electrons move the same distance and have the same charge, the electron with the highest initial potential energy (I) will also have the highest final potential energy at point B. Therefore, we can immediately eliminate choices A and E since they have all the electrons ranked in the same order.

Next, we need to compare the potential energy changes between electrons II, III, and IV. Electrons II and III have the same initial potential energy since they start at the same height, but electron III will have a greater potential energy change since it moves in the same direction as the electric field (from negative to positive potential). Electrons I and IV will have the smallest potential energy changes since they move perpendicular to the electric field and do not experience a change in potential energy.

Therefore, we can rank the electrons from most positive to most negative potential energy change as follows: II > III > I = IV. This matches choice D, so the answer is D.

Four Electrons Move from Point a to Point B in a Uniform