March 1, 1999
Which Battery Is Better?
Batteries come in many shapes and sizes. Some are no larger than a pill while others are
too heavy to lift, but most batteries have one thing in common-they store chemical energy and
change it into electrical energy. The cell is the basic unit that produces electricity. A battery has
2 or more cells, but people often use the word battery when talking about a single cell, too, like a
dry cell. A dime-sized battery in a watch is a cell. Cells act like pumps to force electrons to flow
along conductors (DK Science 150).
“The electrical force of a cell or battery is called its electromotive force (emf). This force,
which makes electrons flow around a circuit, is measured in units called volts (v.). Each kind of
cell has a particular emf. A dry cell, for example, has an emf of 1.5 volts” (DK Science 150).
Another way to measure a battery is by how much current it can provide. Current
measures how many electrons flow through the cell. The unit used to measure current is amps.
A common cell has several important parts: the positive terminal and electrode, the
negative terminal and electrode, and the electrolyte, which is between the two electrodes. The
positive electrode is made out of a carbon rod. Powdered carbon and manganese oxide prevents
hydrogen from forming on the carbon rod, which would stop the cell from working normally.
The negative electrode is made out of zinc, which serves, as a case for the cell. Electrons flow
from the negative terminal through a wire in the device the battery is powering in to the positive
terminal (Learning Center).