A student is investigating the distribution of charge in a conductor. He attaches two unopened soda cans on their sides to two foam cups with tape. He sets the soda cans with the cups onto a tabletop so that they are touching one another. Then he moves a negatively charged balloon close to the left soda can. The set up for the investigation is shown. How do the electrons move in the soda cans?

When the negatively charged balloon is brought close to the left soda can, the electric field from the negatively charged balloon will induce a separation of charges within the conductor (the soda cans).

In the left soda can, the presence of the negatively charged balloon will push some of the electrons in the left can away from the balloon (since like charges repel). This leads to a build-up of negative charge at the bottom and a deficiency of electrons (or positive charge) at the top.

Consequently, in the right soda can, which is in contact with the left can, electrons from the right can will be attracted toward the left can to balance the effect of the negative charge from the balloon.

Therefore, the best description of the movement of electrons is that they move from the right can to the left can.