BATTERIES

A battery is a source of electric current. There are several kinds of batteries, and they come in many size. But they all work on the same principle-they change chemical energy direcly into electrical energy.
A battery is made up two or more units called cells. Sometimes a number of cells are packaged together, as in the battery of a portable radio. Sometimes each cell is separate, as in the ordinary flashlight. That is, what most people call a two-battery flashlight is realy a two-cell plashlight. A single cell can produce electric current, but in many cases it is more practical to use two or more celss and get a greather electrical “pressure,” or voltage. In a two-cell flashlight, each dry cell has a voltage of 1.5. The whole battery ha a voltage of twice that amount, or 3 volts.