The flow of electrons can be accomplished by
several different means: friction, which produces static electricity;
chemicals, which produces electricity in a battery; and magnetism (induction),
which produces electricity in a generator. Other methods are also used, but the
three mentioned here are the most common.
Static Electricity
The oldest method of moving electrons is by
static electricity. Static electricity
produces a flow of electrons by permanently displacing an electron from
an atom. The main characteristic of static electricity is that a prolonged or steady flow of current
is not possible. As soon as the charges between the two substances are equalized
(balanced), electron flow stops.
Friction is usually the cause of static
electricity. Sliding on a plastic seat cover in cold weather and rubbing silk
cloth on a glass rod are two examples of static electricity produced by
friction. Static electricity, no matter what the cause, is merely the permanent
displacement or transfer of electrons. To obtain useful work from electricity,
a constant and steady state flow of electrons must be produced.
Electricity
Through Chemical Means
Electricity
can also be produced by the movement of electrons due to chemical means.
A battery produces an electron flow by a chemical reaction that causes a
transfer of electrons between two electrodes. An electrode is a solid conductor
through which an electric current cap pass. One electrode collects electrons
and one gives away electrons. The dry cell battery uses two electrodes made of
two dissimilar metals inserted in a pastelike electrolyte. Electricity is produced when a chemical reaction occurs
in the electrolyte between the electrodes, causing an electron flow. The construction
of a dry cell battery is shown in Figure 1. A dry cell battery is shown in
Figure 2.
The container of a dry cell battery,, which is
made of zinc, is the negative electrode (gives away electrons). The carbon rod
in the center of the dry cell is the positive electrode (collects electrons).
The space between the electrodes is filled with an electrolyte, usually
manganese dioxide paste. The acid paste causes a chemical reaction between the
carbon electrode and the zinc case. This reaction displaces the electrons,
causing an electron flow. The top of the dry cell is sealed to prevent the
electrolyte from drying and to allow the cell to be used in any position. The
dry cell battery will eventually lose all its power because energy is being
used and not being used and not being replaced.
The storage battery is different from a dry
cell battery because it can be recharged. Thus. It lasts somewhat longer than a
dray cell battery. But it, too, will eventually lose all its energy.
The storage battery consists of a liquid
electrolyte and negative and positive electrodes. The electrolyte is diluted
sulfuric acid. The positive electrodes is coated with lead dioxide and the
negative electrode is sponge lead. The chemical reaction between the two
electrodes and the electrolyte displaces electrons and creates voltage between
the plates. The storage battery is recharged by reversing the current flow into
the battery. The storage battery shown in Figure Figure 3 is commonly used in
automobile electric system.
Electricity Through Magnetism
The magnetic or induction method of producing electron flow uses a conductor to cut through a magnetic field, which causes displacement of electrons. The alternator, generator, and transformer are the best examples of the magnetic method. The magnetic method is used to supply electricity to consumers.
The flow of electrons in a circuit produces
magnetism, which is used to cause movement, or thermal energy, which in turn is
used to cause heat. A magnetic field is created around a conductor-an apparatus
for electrons to flow though-when there is a flow of electrons in the
conductor. The flow of electrons through a conductor with a resistance will
cause heat, such as in an electric heater.
The heating, cooling, and refrigeration
industry uses magnetism to close relays and valves and to operate motors by using
coils of wire to increase the strength of the magnetic field.