What Is Electricity?
We live in the age of electricity. Without electricity we
couldn’t watch television, drive automobiles, make
frozen margaritas, microwave popcorn, read at night,
or talk to our friends on the phone.
Many people think electricity is difficult to understand. They are wrong. Because you are surrounded by
and unconsciously use electrical devices every day, little
lights will go on in your head as you discover the concepts. You’ll probably say, “Oooh—so that’s why my
boat battery is dead every morning!”
I believe you will find electricity to be fun. I am
absolutely sure that, having grasped the very simple
concepts behind boat wiring, you will feel more confident both in your boat and in yourself.
Electricity consists of electrons. An electron is the
smallest quantity of electricity that exists. It is such a
small quantity, however, that we use the unit coulomb
(1 coulomb = 6.24 × 1018 electrons) in calculations.
The flow of electrons is often compared to the flow
of water, so it is natural that we call electron flow “electric current.” The basic unit of electric current is the
ampere (1 ampere = 1 coulomb per second of electrons
moving past a point).
What we usually refer to as electricity is the control
of electrons for useful purposes. Our understanding of
electron behavior allows us to predict the flow of electrons through electrical circuits. The instruments on
your boat contain circuits. Indeed, a boat’s wiring is
no more than a collection of circuits. When we understand circuits, we will understand the behavior of electricity on a boat.
A Circuit
Electrons can be neither created nor destroyed but can
move through conductive materials. An electric current
requires a continuous path of electrically conductive
material, through which the electrons can return to
their source.
If this were not so, electrons would dribble from the
end of wire-like water from a leaky faucet and batteries would soon sit like empty water glasses with all
their electrons lying around them in a pool.
We call a continuous electrical path a circuit. If a circuit is unbroken, we call it a closed circuit. If it is interrupted, preventing the flow of electricity, we say the circuit is open.
All materials present a degree of resistance to electron flow, but the variation is so great that some materials are termed conductors and others insulators.
The best conductors are gold, silver, mercury, copper, and aluminum. Copper is most often the best compromise between cost and conductivity. The best insulators are glass, ceramics, mica, and plastics. Plastic is
the material most often used due to its low cost, durability, and ease of manufacture.
Unfortunately for boaters, salt solutions, such as
seawater, are also good conductors.
Electrical current is expressed as a rate of electron
flow. In a circuit, two factors control the current (I): the
electrical driving force, or voltage (V), and the resistance (R) to flow of the circuit materials.
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