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Lectures in General Physics
Battery
Battery, is a devices that convert chemical energy directly into electrical
energy. Although the term battery, in strict usage, designates an assembly of
two or more voltaic cells capable of such energy conversion, it is commonly
applied to a single cell of this kind.
The mechanism by which a battery generates an electric current involves the
arrangement of constituent chemicals in such a manner that electrons are
released from one part of the battery and made to flow through an external
circuit to another part. The part of the battery at which the electrons are
released to the circuit is called the anode, or the negative electrode; the part
that receives the electrons from the circuit is known as the cathode, or the
positive electrode. (In a device that consumes current--e.g., electroplating
cell, electron tube, etc.--the term anode is often applied to the positive
electrode, while the negative electrode is called the cathode.)
The first battery appears to have been constructed about 1800 by Alessandro
Volta, a professor of natural philosophy at the University of Pavia in Italy.
This device, later known as the voltaic pile, was composed of a series of
silver and zinc disks in pairs, each of which was separated with a sheet of
pasteboard saturated in salt water. A current was produced when the
uppermost disk of silver was connected by a wire to the bottom disk of zinc.
In 1836 the English chemist John Daniell developed what is considered the
classic form of the voltaic cell.
A voltaic cell is composed of two chemicals with different electronattracting
capabilities that are immersed in an electrolyte and connected to
each other through an external circuit. These two chemicals are called an
electrochemical couple. In a zinc-acid cell, for example, the electrochemical
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