Lesson 1/Learning Event 2
In automotive vehicles, insulators must be used to keep the electrons or current in the proper path.
Wire conductors are covered with insulating material, such as rubber, cotton, plastic, or enamel.
Hard materials, such as fiberboard and Bakelite, are used in the ignition system and for switches
where parts need to be mounted securely by a rigid insulator.
CURRENT
Electric current, like the flow of water, can be measured. Water flowing in a pipe is measured by
the number of gallons of water that flow per minute. Electric current is measured by units known
as AMPERES. It takes more than six billion electrons moving past a given point in one second to
make up one ampere.
A device known as an AMMETER is used to measure amperes.
While 1 ampere may sound like a lot, in automotive electricity it is considered a rather small
amount of current. Some lights may require about 1 ampere, but the starter motor requires 100
amperes or more.
VOLTAGE
As we said before, electron flow or current is caused by electron unbalance. In other words, when
one end of a conductor has a positive charge and the other end has a negative charge, electrons will
move to the positive end. The greater the difference in the amount of electrons at opposite ends of
a wire, the greater the pressure will be that is pushing the electrons through the wire. This pressure
is commonly known as potential difference, or VOLTAGE.
Voltage and its effect on electric current in a wire can be compared to pressure and its effect on
water flowing in a pipe. When pressure is increased on water in a pipe, a greater volume of water
will flow in a given period. If the voltage of an electrical circuit is increased, a greater number of
electrons will move--more current will flow.
Voltage is measured with a VOLTMETER, which will be covered in detail later.
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