Cells and Batteries
IN ELECTRICITY, WE CALL A UNIT SOURCE OF DC ENERGY A CELL. WHEN WE CONNECT TWO OR MORE cells in series, parallel, or series-parallel, we obtain a battery. Numerous types of cells and batteries exist, and inventors keep discovering more.
Early in the history of electricity science, physicists noticed that when metals came into contact with certain chemical solutions, a potential difference sometimes appeared between the pieces of metal. These experimenters had discovered the first electrochemical cells.
A piece of lead and a piece of lead dioxide immersed in an acid solution (Fig. 7-1) acquire a persistent potential difference. In the original experiments, scientists detected this voltage by ...