Answer:
In primary cells, an electric potential develops through chemical action between the plates within the cell. Positively charged ions of zinc enter the acid and free electrons released from zinc atoms collect on the zinc plate, which results in a negative charge. At the same time, positively charged ions of hydrogen from the acid remove free electrons from the copper plate, which becomes positively charged. Through a conducting material connecting the plates, free electrons move from the zinc plate to the copper plate as long as the chemical reaction lasts.
Dry cells also develop electric potential via chemical actions within the cell. Free electrons removed from the carbon rod collect on a zinc can. The rod exhibits a positive charge and the can becomes negatively charged; this allows for an electric potential to develop between these two items. Through a conducting material connecting the can to the rod, free electrons move from the can to the rod as long as the conducting path exists.
Step-by-step explanation:
straight from Penn