After
reading this section you will be able to do
the following:
Contrast
the characteristics of conductors and insulators.
List examples
of common conductors and insulators.
Explain
how insulators provide protection from electricity.
In the previous pages, we have talked
a bit about “conductors” and “insulators”.
We will discuss these two subjects a little more before moving
on to discuss circuits.
Conductors
Do you remember the copper atom that
we discussed? Do you remember how its valence shell had an electron
that could easily be shared between other atoms? Copper is considered
to be a conductor because it “conducts” the electron
current or flow of electrons fairly easily. Most metals are considered
to be good conductors of electrical current. Copper is just one
of the more popular materials that is used for conductors.
Other materials that are sometimes
used as conductors are silver, gold, and aluminum. Copper is still
the most popular material used for wires because it is a very
good conductor of electrical current and it is fairly inexpensive
when compared to gold and silver. Aluminum and most other metals
do not conduct electricity quite as good as copper.
Insulators
Insulators are materials that
have just the opposite effect on the flow of electrons. They do
not let electrons flow very easily from one atom to another. Insulators
are materials whose atoms have tightly bound electrons. These
electrons are not free to roam around and be shared by neighboring
atoms.
Some common insulator materials are
glass, plastic, rubber, air, and wood.
Insulators are used to protect us
from the dangerous effects of electricity flowing through conductors.
Sometimes the voltage in an electrical circuit can be quite high
and dangerous. If the voltage is high enough, electric current
can be made to flow through even materials that are generally
not considered to be good conductors. Our bodies will conduct
electricity and you may have experienced this when you received
an electrical shock. Generally, electricity flowing through the
body is not pleasant and can cause injuries. The function of our
heart can be disrupted by a strong electrical shock and the current
can cause burns. Therefore, we need to shield our bodies from
the conductors that carry electricity. The rubbery coating on
wires is an insulating material that shields us from the conductor
inside. Look at any lamp cord and you will see the insulator.
If you see the conductor, it is probably time to replace the cord.
Recall our earlier discussion about
resistance. Conductors have a very low resistance to electrical
current while insulators have a very high resistance to electrical
current. These two factors become very important when we start
to deal with actual electrical circuits.
Review
Conductors
conduct electrical current very easily because of their free
electrons.
Insulators
oppose electrical current and make poor conductors.
Some common
conductors are copper, aluminum, gold, and silver.
Some common
insulators are glass, air, plastic, rubber, and wood.
