If holes are in excess, it is a p-type. P for positive. Where they join is called the p-n junction. In this area, some electrons and holes cancel each other out. A thin layer forms, that acts like an insulator.
Cells connected in series make a battery.
The number of cells determines its nominal voltage. During discharge, the chemical energy of the plates is transformed into electrical energy, then used to perform work. The plates develop the same composition, which reduces the potential of the cell. Ohm's Law Ohm's Law Ohm's Law states that current flow in a circuit varies in direct proportion to changes in voltage, and in inverse proportion to the changes in resistance. In an electrical circuit, the unit of power is the watt.