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00917_Field_917.txt
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1997-05-26
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Background Information
Current electricity is created
by a flow of tiny particles
called electrons. The electrons have to have a
closed path to travel along.
This path is called a circuit. A circuit usually has at least
three parts: a source of
electrical energy, such as a
battery; a substance for the
electricity to travel in, such
as wire; and something that
uses the electricity, such as
a light bulb.
A switch is used to open
and close a circuit. When
the circuit is closed,
electricity can flow through
the circuit. When the circuit
is open, electricity cannot
flow through the circuit.
Some circuits also contain
devices called resistors.
Resistors change how easily electrons can move
through the circuit.
There are two types of
circuits, series circuits and
parallel circuits. In a series
circuit, all the parts of the
circuit are connected one
after the other. The current
can follow only one path. In
a parallel circuit the parts are connected in different
ways, so the electricity can
follow more than one path.